Case studies

The case can be used in the subject areas of marketing, strategy, business model innovation, and general business growth, particularly those with a focus on emerging markets.

This case can be used in postgraduate and post-experience business courses such as Master's degrees in Business Administration, postgraduate diplomas, executive education, or specialist Master's degrees.

This case looks at craft beer business Jack Black's Brewing Co. started in 2006 in Cape Town. After humble beginnings, protagonist McCulloch grew the company rapidly with a focus on the strategic “tap” market across the country. After systematically working with a number of contract brewers the company finally invested in their own, industrial-scale brewery and brewpub. The dilemma facing McCulloch and Jack Black's Brewing Co. is one of cash flow. In order to generate cash flow, the management team needs to drive sales so that the brewery operates at full capacity. While it strives to attain this goal, there are considerable cash flow and liquidity challenges.

The development of an understanding of an effective marketing mix to position a niche and young brand.

An understanding of the concept “co-opetition” and how it works in a growing market.

The ability to assess the various growth stages of a business.

The case can be used in the subject areas of marketing, strategy, business model innovation in an emerging market. The case introduces a practical example of brand extension as a growth strategy employed by an existing brand to secure additional revenue channels and customer touch points.

This teaching case is aimed at postgraduate business students such as Master's degrees in Business Administration degrees, postgraduate diplomas, executive education, or specialist Master's degrees.

Kauai is a health restaurant with 150 stores across South Africa, Namibia and Botswana, more than 50% of which are franchise-owned. An acquisition of the original Kauai quick-service restaurant (QSR) chain by Real Foods in 2015 leads to a complete rebrand and overhaul of its product offering and store experience. Since the acquisition, the business operates as a startup with few formal processes and KPIs in place to drive performance. Despite the obvious success the team is battling with the factors that need to be considered to ensure that they can scale adequately to realise full potential. Plus how should they position the existing brand effectively within the FMCG space to maximise the contribution of brand equity to its success?

–The understanding around the business model of a strong, existing brand entering a highly competitive and price-sensitive FMCG.

–Analysing the marketing strategy and brand identity approaches that could be used.

–An understanding of the brand extension strategy that could be implemented in light of various challenges.

–Understanding how retail marketing works in an emerging market context.

Steel Corp has a large production capacity but a shrinking steel market in Europe. Reaching growing markets like China and U.A.E will be important to sustaining and growing revenue but is tough due to higher transportation costs. In this case, users must identify and use logistics data; logistics customer segmentation and related cost analysis.

The COO for Suape Container Terminal, the largest deep–water port in Brazil's Northeast must consider a proposal presented by the users' council that calls for the establishment of a reservation scheme that minimizes the risk of docking delays. Under this proposal, ocean carriers, on the one hand, agree to pay a reservation fee that significantly increases revenue for Tecon Suape. On the other hand, they expect Tecon Suape to compensate them financially when a berth is not available upon vessel arrival. Tecon Suape's management team must evaluate that suggestion, as the team prepares to enter contractual negotiations with the users.

Faced with declining market share and sales, Natura, Brazil’s second-largest brand in the cosmetics, fragrances, and toiletries market, expanded its customer reach by moving from a direct-sales company to a multichannel company. In 2014, Natura added online catalogs, physical stores, and drugstores to its well-established direct-selling model, but the results were disappointing. Between 2014 and 2016, three different Natura CEOs attempted to lead the company in the strategic transition to focus less on the direct sales consultants and more on reaching the end consumers directly with multiple channels and touchpoints. In October 2016, the company’s board appointed its former commercial vice president, João Paulo Ferreira, as the most recent CEO. Ferreira’s challenge was to find the right balance between the direct-selling and other channel formats to market Natura, thus enabling it to thrive in the face of intense competition in the beauty and personal care market in Brazil.

At three o'clock in the morning on September 10, 2001, Thierry Hautillac, a risk arbitrageur, learns of the final agreement between Pinault-Printemps-Redoute SA (“PPR”) and LVMH Moët Hennessy Louis Vuitton SA (“LVMH”). After a contest for control of Gucci lasting over two years, PPR has emerged as the winner. PPR and LVMH have agreed for PPR to buy about half of LVMH's stock in Gucci for $94 per share, for Gucci to pay an extraordinary dividend of $7 per share, and for PPR to give a two and a half year put option with a strike price of $101.50 to the public shareholders in Gucci. The primary task for the student in this case is to recommend a course of action for Hautillac: should he sell his 2% holding of Gucci shares when the market opens, continue to hold his shares, or buy more shares? The student must estimate the risky arbitrage returns from each of these choices. As a basis for this decision, the student must value the terms of payment and consider what the Gucci stock price will do upon the market's open. The student must determine the intrinsic value of Gucci using a DCF model as well as information on peer firms and transactions. The student must consider potential synergies between Gucci and PPR and between Gucci and LVMH. The student must assess the likelihood of a higher bid, using analysis of price changes at earlier events in the contest for clues.

In early 2012, an equity analyst, was examining the jet fuel hedging strategy of JetBlue Airways for the coming year. Because airlines cross-hedged their jet fuel price risk using derivatives contracts on other oil products such as WTI and Brent crude oil, they were exposed to basis risk. In 2011, dislocations in the oil market led to a Brent-WTI premium wherein jet fuel started to move with Brent instead of WTI, as it traditionally did. Faced with hedging losses, several U.S. airlines started to change their hedging strategies, moving away from WTI. But others worried that the Brent-WTI premium might be a temporary phenomenon. For 2012, would JetBlue continue using WTI for its hedges, or would it switch to an alternative such as Brent?

This case depicts the history of an unusual brand in the “super premium” segment of the vodka market. The top-of-line positioning is supported with creative advertising, narrow distribution, point-of-purchase advertising, and expensive advertising production. Absolut has used very expensive inserts as advertisements in print vehicles during the Christmas season. The last inserts described in the case cost approximately $1 each to manufacture and distribute via the media vehicle (The New Yorker). The case asks students to decide whether such expensive advertising should be continued and, if so, how. The societal effects of advertising alcoholic beverages and the implications of pursuing such exclusive positioning strategies may also be explored.

This case is used in Darden's core Marketing course and in the Pricing elective. It would work well in course modules covering the topics of branding or product line management. A teaching note is available for instructors. Soon after Pernod Ricard acquires Absolut vodka and other brands, the economic downturn results in changes in purchasing behavior away from premium to standard products. Brand managers consider whether to introduce a “basic” Absolut, promote a lower-priced alternative, or rebrand other vodkas under the Absolut brand to trade on its considerable brand equity.

This case challenges students to apply financial reporting concepts pertaining, most notably, to liabilities and expenses in a specific corporate situation. In the context of an interesting, but noncomplex, technical accounting issue, students debate the best way for Adenosine Therapeutics to present its compensation arrangements in its financial statements. In addition, this case also prompts students to debate the best way for a growing company, with cash constraints, to provide incentive and maintain top employees.

Executives at this Internet-based company evaluate the results of a pricing survey to decide what changes to make, if any, to the annual fee charged for the company’s junk mail elimination services. Founded in 1996, Adios Junk Mail provides comprehensive elimination of unwanted direct-marketing solicitations. Clients select what types of direct marketing they want stopped. Once a month, the company generates a list of customers and their elimination preferences. It then mails the list to direct-mail companies, telemarketers, and database companies, requesting that the customers’ names be suppressed.

This case is intended to be part of a first-year MBA marketing course, or a second-year elective in advertising, integrated marketing communications, market research, or marketing analytics. The case provides students with examples of two real advertising experiments and the challenges involved in executing the experiments. It allows for a discussion of the need for advertising experiments, and also, at a more general level, the need to measure the return on marketing. Biases surrounding the field experiments allow for a discussion of the problems with establishing a causal relationship between advertising and sales.

This case raises the question: How does a company reasonably estimate and record entries for uncollectible trade receivables, and under what circumstances are receivables written off as uncollectible? The required accounting transactions for the case involve estimating a receivables allowance both as a percentage of sales and as a percentage of accounts receivable and making specific account judgments under the direct write?off method. The subjective issues involve analyzing and assessing a company's methods of collection and accounting for bad debts.

Students act as outside analysts attempting to determine how Alfin will finance its expected growth based on sales of antiwrinkle cream.

While preparing a financial forecast, the newly promoted CFO of a small and profitable but financially constrained ready-mix concrete company must choose between renegotiating debt obligations, postponing long overdue capital improvements that will prevent more costly future repairs, or reducing the dividend payment to a parent company that just recently purchased the firm.

After having negotiated major financial and operating decisions with its parent company, the CFO of this small ready-mix concrete subsidiary is asked to provide a valuation of the subsidiary. A one-year forecast of financial statements is provided along with information on long-term operating expectations and capital costs. This otherwise straightforward valuation exercise is enhanced by (1) the need to select between the parent- or comparable-firm costs of capital, (2) sufficient guidance to perform an illuminating sensitivity analysis, and (3) a sufficiently clear and rich context in which to illustrate the linkages between operating and financing choices. A teaching note and instructor and student Excel spreadsheets are available.

This case is used in Darden's FY Finance course, but it would be appropriate in any course introducing firm valuation. The case examines the 2012 decision by American Greetings (AG) to repurchase shares. Students can build a simple model of the company's future cash flows and derive an implied value. Because the company is arguably in a state of maturity or decline, a discussion of steady-state economics is particularly germane.

Set in September 1992, this exercise provides teams of students the opportunity to negotiate terms of a merger between AT&T and McCaw Cellular. AT&T, one of the largest U.S. corporations, was the dominant competitor in long-distance telephone communications in the United States. McCaw was the largest competitor in the rapidly growing cellular-telephone communications industry. Prior to the negotiations, AT&T had no position in cellular communications. This case and its companion (F-1143) are designed to allow students to be assigned roles to play. The case may pursue some or all of the following teaching objectives: exercising valuation skills, practicing strategic analysis, exercising bargaining skills, and illustrating practical aspects of mergers and acquisitions.

This case is one of a pair of cases used in a merger negotiation. It is designed to be used with “British Petroleum, Ltd.” (UVA-F-1263). One-half of the class prepares only the British Petroleum (BP) case, and one-half uses this case. BP and Amoco are considering a merger, and are in the process of negotiating a merger agreement. Macroeconomic assumptions, particularly forecasting future oil prices in an uncertain environment, and assumptions about Amoco's ability to reduce exploration and production costs make Amoco's future cash flows difficult to predict.

In August 2005, an investment manager of a hedge fund is considering purchasing an equity interest in a start-up biotechnology firm, Arcadian Microarray Technologies, Inc. The asking price is $40 million for a 60 percent equity interest. Managers of the firm are optimistic about the firm's future performance; the investment manager is more conservative in his expectations. He calls on the help of an analyst with her firm to fashion a counterproposal to Arcadian's management. The tasks for the student are to apply the concept of terminal value, interpret completed analyses and data, and derive implications of different terminal-value assumptions in an effort to recommend a counterproposal. Very little numerical figure-work is required of the student.

A new CEO from outside the firm takes over following the sudden death of the former CEO. Included in the new CEO's inbox are pressing decisions concerning (1) the firm's financing needs, (2) capital equipment, and (3) a general assessment of the firm's financial performance. The task for the student is to analyze these issues and recommend action.

The case examines one of the most significant infrastructure projects in southeastern Europe during a time when the legal and financial environment for project financing was in its infancy (early to mid-1990s). Athens needed a ring road to support its bid to host the 2004 Olympic Games. The road was technically—as well as logistically—complex, involving 33 municipalities and construction that involved a major metropolitan area (Athens) populated by more than 3.5 million inhabitants. The case examines the economics of the project, how private-public partnerships (PPPs) are structured, and the broader field of infrastructure finance.

This case asks the student to decide whether Aurora Textile Company can create value by upgrading its spinning machine to produce higher-quality yarn that sells for a higher margin. Cost information allows the student to produce cash-flow projections for both the existing spinning machine and the new machine. The cash flows have many different cost components, including depreciation, the number of days of cotton inventory, and the liability costs associated with returns from retailers. The cost of capital is specified in order to simplify the analysis. The analysis has added complexity, however, owing to the troubled financial condition of both the company and the U.S. textile industry, which is in decline as manufacturers migrate to Asia to benefit from lower manufacturing costs. This begs the question whether management should invest in a declining business or harvest the company by paying out all profits as a dividend to the owners. The case is suitable for students just beginning to learn finance principles, but is also rich enough to use with experienced students and executives. The primary learning points are as follows:

• The basics of incremental-cash-flow analysis: identifying the cash flows relevant to a capital-investment decision

• The construction of a side-by-side discounted-cash-flow analysis for a replacement decision

• How to adapt the NPV decision rule to a troubled or dying industry

• The effect of financial distress on the NPV calculation

• The importance of sensitivity analysis to a capital-investment decision

The basics of incremental-cash-flow analysis: identifying the cash flows relevant to a capital-investment decision

The construction of a side-by-side discounted-cash-flow analysis for a replacement decision

How to adapt the NPV decision rule to a troubled or dying industry

The effect of financial distress on the NPV calculation

The importance of sensitivity analysis to a capital-investment decision

The case can be taught in an introductory corporate finance course or to more experienced students or executives to spur a discussion about share repurchases and corporate financial strategies in general. If used in an introductory course, the case is most effective if preceded by a traditional dividend class. It follows a portfolio manager of Johnson & Associates, Mark Johnson, who is reviewing his holdings, including his position in AutoZone in early 2012. A prominent shareholder, Edward Lampert, had begun liquidating his position in AutoZone, and Johnson is concerned that Lampert's reduced position could lead the company to stop using share repurchases as a method of distributing cash flows to shareholders. The case lists a number of alternative uses for the cash flows and asks students to assume Johnson's role as an analyst and assess the likely impact of those alternatives on AutoZone's stock price.

A small adhesives company faces exchange rate risks as it makes its first foray into international sales. The receipt of payment from an unhedged foreign-currency-denominated past sale illustrates potential currency risks while a potential follow-on order provides a context to discuss potential hedges. Sufficient detailed information is provided for the students to construct and analyze both a forward and money market hedge. A teaching note and instructor and student Excel spreadsheets are available.

This case serves as an introduction to field sales management. A manager must address three sales representatives' ingrained behaviors in order to implement a major shift in marketing strategy. Students should recognize the nature of the "man-in-the-middle" squeeze: the manager caught between the pressure of implementing a new strategy from the top and the resistance to change from the bottom.

A new director of this small brewery must prepare to vote on three issues coming before the board of directors the next day: (1) approval of the financial plan for 1993, (2) quarterly dividend declaration, and (3) incentive-compensation plan for the marketing manager. The tasks for the student are to evaluate the past and prospective financial performance of the company and to assess the extremely liberal credit and inventory terms the company is extending to its distributors. The objective of the case is to introduce and exercise tools and concepts of financial-statement analysis. Perhaps the biggest insight gained by students concerns the link between incentives and financial performance: in this case, the marketing manager is motivated to build sales volume, which he accomplishes by a dramatic buildup in receivables and inventory.

The case has been used in a first-year required course called Global Economies and Markets in a module on monetary policy. On October 24, 2005, President Bush nominated Ben S. Bernanke to be chairman of the board of governors of the Federal Reserve System for a term of four years along with a 14-year term on the board of governors. With the U.S. Senate confirmation widely anticipated, Bernanke was expected to take over stewardship of the U.S. monetary policy from Chairman Alan Greenspan when he retired in January 2006. While the U.S. economy was in good shape at the end of 2005, Bernanke had to prepare to deal with two challenges when charting a course for managing U.S. monetary policy. First, the sharp rise in energy prices that began in 2002 had the potential to bring back the specter of inflation and dampen desired consumer and business spending. Second, the housing boom could turn into a housing bust, throwing the mortgage industry into turmoil and weakening consumer business confidence. There was also the possibility that the housing bust could affect broader financial markets. Bernanke had to consider his options for dealing with contingencies in the not-so-distant future.

Benecol Spread, a cholesterol-lowering margarine, was a product with unusual media-planning challenges. With a narrow target group and unproven market potential, Johnson & Johnson needed to get the most “bang for the buck” from its Benecol advertising. Would a media-planning model (optimizer) requiring executives to quantify their judgment on several key inputs be helpful in this process? A spreadsheet accompanying the case allows students to weight the target groups and to choose among different advertising vehicles to form the best possible media plan.

This case pertains to one of the most important topics in financial accounting and reporting: revenue recognition. It is intended for use in a required MBA financial accounting course or in an MBA elective course in Financial Reporting and Analysis. The company, Better Buy, Inc., is an electronics retailer selling TVs and other electronic products. The company is a bit unique, however, in that it not only sells major brand TVs, but it also sells TVs under its own brand that carry a one-year warranty for which the retailer—not the manufacturer—is responsible. The company also offers an additional two-year warranty on its TVs that also is the sole responsibility of the retailer. The case asks students to address a number of revenue recognition situations along with the associated expenses. These situations include a product sale where the sales price also includes a warranty provision, a “bundle” of a product sale and an extended warranty sale, and a bundle of a product sale and an extended warranty sale where the company has an agreement to outsource the servicing of its extended warranty service

This case has been significantly revised to update its currency and to be more concise. In early 2015, two partners in an Oklahoma medical practice must reconcile their booming urology business with declines in practice cash flow. The case highlights the difference between cash flow and accounting profits, as well as the common negative effects of growth on cash flow. It provides a straightforward introduction to simple financial-statement modeling and an opportunity to develop intuition on the importance of cash flow to business owners. The case is tailored to an audience with a professional business-practice perspective.

Lee High, the newly hired cost accountant at Blackheath Manufacturing Company, computes the variable cost and the fixed cost per unit on a weekly volume of 500 units of the Great Heath. He uses this information to develop some pricing guidelines. His boss, Charlton Blackheath, endorses the guidelines and adds a feature: a higher commission on sales at a higher price. While both High and Blackheath are away, the file clerk, Adelaide Ladywell, accepts an order below the guidelines and is fired. Students are asked to develop an appropriate set of decision rules for pricing Great Heath and to evaluate Ladywell's decision. See also “Blackheath Manufacturing Company—Revisited” (UVA-C-2198).

It's panic time at Blackheath Manufacturing. Profits have been declining, so the owner's son comes to the rescue to run the company. He asks a consultant to determine what's wrong. And the consultant has specific answers: The company's pricing guidelines are all wrong, there needs to be a budgeting system to reverse the downward slide in profits, and a former employee should be rehired. This case provides students with the data for constructing a production and raw-materials budget, flexible-expense budget, income statement, balance sheet, and cash budget. See also “Blackheath Manufacturing Company” (UVA-C-2197).

In May 1999, the CEO of this company (the largest brewer in Brazil) is contemplating a bid for Antarctica, the second-largest brewer in Brazil. The primary motives are to exploit economies of scale and other synergies and to prevent other competitors (mainly foreign multinationals) from acquiring the firm. The tasks for the student are to value the target and buyer, propose an exchange ratio of shares, and generally design the terms of the transaction.

The student's task is to develop a comprehensive strategy for Briggs & Stratton, which is facing severe competition and margin pressures. A major component of the strategy to be considered is whether to implement economic value added (EVA) as a new performance measurement for management. The case is designed to serve as an introduction to how to compute and use EVA. It emphasizes the importance of performance evaluation as part of a larger strategic plan. A teaching note is available to registered faculty, as well as two video supplements to enhance student learning.

This case is one of a pair of cases used in a merger negotiation. It is designed to be used with “Amoco Corporation” (UVA-F-1262). One-half of the class prepares only the Amoco case, and one-half uses this case. BP and Amoco are considering a merger, and are in the process of negotiating a merger agreement. Macroeconomic assumptions, particularly forecasting future oil prices in an uncertain environment, and assumptions about Amoco's ability to reduce exploration and production costs make Amoco's future cash flows difficult to predict.

The director of equipment finance at Burlington Northern Railroad Company must decide if a leveraged-lease proposal is acceptable. The case emphasizes the importance of the lessee's tax status to the value of the lease and how the perception of residual value affects the valuation for both the lessee and lessor. To value the lease properly, the student must identify the relevant cash flows and the appropriate discount rates for those flows.

Cardagin, a new start-up in the increasingly competitive space of consumer/merchant apps for smartphones, is reaching an inflection point: decisions it makes at this stage can determine whether it becomes a national presence or an also-ran. The CEO needs to demonstrate the value of Cardagin's service to retailers and consumers in compelling ways. The case provides students an opportunity to analyze a new digital venture, explore expansion options, and evaluate the challenges in working with many small businesses, each with its own idiosyncrasies.

A growing folding carton company is contemplating the replacement of an old machine with a new one. The case challenge is to develop a cash flow forecast and determine the proper discount rate for the machine replacement. In addition to increased capacity and reduced waste, the new machine offers strategic advantages to the firm in its chosen market niche. Issues related to operations are central to appreciating the importance and implications of this capital investment: Operating excellence is a key competitive advantage for this firm. A teaching note and student and instructor Excel spreadsheets are available to accompany the case for instructors.

A midsize community hospital must choose a strategy to compete with an expanding regional rival. The strategy, focused on acquiring patient volume, includes expanding investment into integrated care, setting the reimbursement structure for revenue collection, and moving to a capitation-based payment system. The case presents an evaluation of revenue models to select that which best supports a given business strategy.

This case is designed to introduce a health care audience to financial analysis. It provides a straightforward introduction to hospital financial-statement ratio analysis and hospital operating statistics, so it can also serve to introduce any audience with a business or medical background to hospital finance.

This case may be taught singly or used as a merger-negotiation exercise with “Daimler-Benz A. G.: Negotiations between Daimler and Chrysler” (UVA-F-1241). Set in February 1998, the case places students in the position of negotiators for the company; their task is to value both firms, assess the potential earnings dilution of a combination, and negotiate a detailed agreement with their counterpart. The case can be used to explore such interesting negotiation issues as determination of a share-exchange ratio, treatment of major stockholders, and structuring a deal. Also, the case and exercise can be used to spark a discussion of acquisition in comparison with strategic alliance, or other less formal models of combination.

This case is a vehicle for discussing the theory and practice of option pricing through the valuation of warrants of Chrysler held by the U.S. government and of the loan guarantee provided by the U.S. government to Chrysler.

Lilly ICOS is preparing to launch Cialis, a prescription drug that treats erectile dysfunction, and executives must decide how to position Cialis against market leader Viagra and recent entrant Levitra.

Acting as chief financial officer (CFO), students try to determine how Coleco can fend off creditors. Coleco is in default on its loans and is in a negative equity position.

In early September 2008, in the midst of the subprime crisis, a manager with the student-run Darden Capital Management fund, wants to evaluate whether Comerica Incorporated, a regional bank based in Dallas, Texas, is a good candidate for inclusion in his portfolio. He needs to perform a valuation of the bank to assert whether the bank seems to be undervalued by the market or whether a further decline in value might be possible. He must account for all the factors that affect bank valuation, both as related to the bank itself as well as to the current market conditions. The case can be taught to: a) examine the valuation of a bank during turbulent times; b) understand the key accounting statements (balance sheet and income statement) for a bank and how they may differ from those for an industrial company; and c) understand the key value drivers of bank value (metrics for profitability, credit quality, liquidity, and capital).

The cofounder of Compass Records, a small, independent music-recording company, must decide whether to “produce and own” the next album of an up-and-coming folk musician or simply “license” her finished recording. This case presents information sufficient to build cash-flow forecasts for either investment alternative. Discounted cash flow (DCF) analysis reveals that licensing will be the more attractive alternative unless the student assesses the value of the options for follow-on albums included in the “produce-and-own” contract.

In February 1994, the senior management team at Continental Cablevision received the final joint-venture agreement from Fintelco, a potential partner in Argentina. The tasks for the student are to review the terms of the agreement, the outlook for the Argentine economy, and the corporate cultures at both companies to decide whether Continental should sign the agreement.

This case reviews different varieties of currency crises and two in particular: United Kingdom in 1992 and Hong Kong in 1998. These were two very different types of crises, and understanding them could serve the protagonist well when future crises occurred.

This case may be taught singly or used as a merger-negotiation exercise with “Chrysler Corporation: Negotiations between Daimler and Chrysler” (UVA-F-1240). Set in February 1998, the case places students in the position of negotiators for the company; their task is to value both firms, assess the potential earnings dilution of a combination, and negotiate a detailed agreement with their counterpart. The case can be used to explore such interesting negotiation issues as determination of a share-exchange ratio, treatment of major stockholders, and structuring a deal. Also, the case and exercise can be used to spark a discussion of acquisition in comparison with strategic alliance, or other less formal models of combination.

The investment-strategy decisions of a Darden Capital Management student-portfolio management team in 2004 are examined. Case materials allow students to estimate CAPM-based expected returns using market data. The case focuses on introducing the portfolio-allocation decision; exploring the relevance of various investment-risk metrics; developing the intuition of diversification, market risk, and the capital-asset-pricing model; building judgment on how to appropriately estimate the CAPM parameters using available market data; and discussing the fundamental concepts of market efficiency.