Noted value investor Bill Miller is the former chairman and chief executive officer of Legg Mason Capital Management. He is the portfolio manager of the Legg Mason Opportunity Fund, but it is his run at the helm of the Legg Mason Value Trust Fund, now the ClearBridge Value Trust Fund, that established his legacy as a top investor.

Under Miller's guidance, the Value Trust Fund's after-fee return beat the S&P 500 for 15 consecutive years from 1991 through 2005. For as much success as Miller experienced during this period, the subsequent six years were just as disappointing. The Value Trust Fund only beat the S&P 500 once from 2006 to 2011. Miller left the Value Trust Fund at the end of 2011 to focus on managing the Opportunity Fund.

While Miller's style is to favor deep value plays and make sizable bets on them, he has also demonstrated a willingness to invest in richly priced stocks if he feels the value of future growth outweighs current valuations. Additionally, he has targeted companies or areas of the market that are unloved by popular opinion. Miller's portfolio reflects all aspects of his investing style. The following are his five largest holdings as of Dec. 31, 2015.

Microsoft Corp.

Miller's biggest portfolio holding is Microsoft Corp. (NASDAQ: MSFT), though the company's valuation metrics do not necessarily suggest a pure value play. As of Feb. 10, 2016, its forward price-to-earnings (P/E) ratio is 17, similar to that of the S&P 500 Index. Microsoft has, however, shown strong demand for its recent product releases.

Windows 10 upgrades are outpacing those of Windows 8.1 and Windows XP. Office 365 has provided cloud capabilities and flexibility for both private consumers and businesses. Microsoft's Surface tablet, while not nearly as successful as Apple's iPad, also demonstrated strong sales growth in the fourth quarter of 2015. Analysts worried that Microsoft would fall victim to the broad shift away from desktop computers are seeing the company still has the ability to adapt and grow. As Miller's largest portfolio holding, Microsoft comprises 4.01% of his portfolio's total assets.

Citigroup Inc.

Citigroup Inc. (NYSE: C) represents the more traditional value play favored by Miller. The Fed's zero interest rate policy coupled with ongoing global growth concerns have beaten down the valuations of financial companies to the point where they represent a good long-term value.

Much of the profitability of banks depends on interest rates. With the federal funds rate at near zero for the past six years, banks' profits from loans have dwindled, since rates on those loans have remained near record low levels. Conversely, higher interest rates on loans mean more revenue for the banks. The Federal Reserve raised the federal funds rate for the first time in six years in December 2015, and the prospect of additional rate hikes in the future provides optimism for bank stock shareholders. Citigroup is Miller's second-largest holding, comprising 3.36% of his portfolio's assets.

Calpine Corp.

Calpine Corp. (NYSE: CPN), a utility that operates primarily in the natural gas industry, fits the definition of unloved. The company declared bankruptcy in 2005, and its stock has been hit hard along with the rest of the energy sector as commodity prices have fallen. As of Feb. 10, 2016, the stock is off nearly 50% from its near-time high. However, the company is delivering strong free cash flow and has an intriguing portfolio of assets to help it continue to do so. Calpine is Miller's third-largest holding, comprising 3.15% of his portfolio’s assets.

Amazon.com Inc.

Amazon.com Inc. (NASDAQ: AMZN) has been an expensive stock from the moment it became a publicly traded company nearly two decades ago. Therefore, it has never been popular with traditional valuation metrics, since the company has long eschewed profitability in favor of funding future growth.

Miller feels that Amazon's risk-reward circumstance outweighs the perceived overvaluation of its stock. He claims that traditional valuation metrics apply to more traditional companies, and Amazon's place as a retail disruptor was the overall deciding factor for him. Amazon is Miller's fourth-largest holding, comprising 3.08% of his portfolio’s assets.

Wells Fargo & Company

Miller's investment in Wells Fargo & Company (NYSE: WFC) falls into the same category as Citigroup, as it is another company whose traditional valuation metrics suggest it could be a bargain. This company, which operates in consumer and commercial banking, mortgages, wealth management and brokerage services, maintains a P/E ratio of around 10, which is almost half that of the broader market.

Wells Fargo is broadly diversified and profitable. In the fourth quarter of 2015, the company delivered deposit growth, improving credit portfolio quality and profitability among all of its major lines of business. Wells Fargo is Bill Miller's fifth-largest portfolio holding, representing 2.76% of his portfolio’s assets.

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