Updated at 5:15 p.m. on June 26, 2009

Warren Buffett, the billionaire head of Berkshire Hathaway (BRK.A), is the second-richest man in the world, after Bill Gates and ahead of Carlos Slim Helu. He is considered one of the leading value investors, and although Berkshire has taken a major hit recently, over the years it has performed extremely well. An $8,200 investment in the company in January of 1990 would now be worth more than $86,000.

So it makes you wonder why traders would short the stocks that Buffett chose for his Berkshire portfolio. Since many of his stocks have dropped and some are heavily shorted, there may be some short-squeeze opportunities to take advantage of.

A short squeeze takes place when short sellers quickly buy in shares of the stock in order to cover their positions, driving the price of stocks up sharply. The ratio for measuring short squeeze opportunities is the short ratio, which is the number of days it would take the short sellers to cover their position based on recent average daily volume.

Stockpickr has reviewed the stocks owned by Warren Buffett and their short ratios and has compiled with a portfolio of the Top Buffett Short-Squeeze Plays.

One heavily shorted Buffett stock is CarMax (KMX), a retailer of new and used vehicles, which has a short ratio of 8.7. This means that it would take more than 8 days for the short-sellers to cover their positions, based on recent trading volume. Deutsche Bank recently downgraded the stock from buy to hold but raised its price target from $15 to $17 and boosted its EPS estimate from 38 cents to 57 cents per share. CarMax has operating cash flow of $105.8 million, total debt of $417.6 million and cash in the banks of $133.5 million.

On Monday, CarMax closed up 4 cents, or 0.3%, at $14.52.

CarMax is favored by another top value investor, Arnold Van Den Berg, the chairman of the Board of Trustees at Van Den Berg Management, also known as Century Management, which he founded in 1974. Van Den Berg has recently acquired several other stocks, including Wal-Mart Stores (WMT), with a short ratio of 1.7; 3M (MMM), with a 2.5 short ratio; and Avery Dennison (AVY), with a fairly high 4.9 short ratio.

Another Buffett stock that is heavily shorted is Iron Mountain (IRM), an information protection and data storage company, which has a short ratio of 11. Back in April, it reported that its first-quarter net profit dropped by 14% to 14 cents a share, down from 16 cents a share for the same quarter for the previous year. However, it beat analysts' consensus forecast of 12 cents a share, and it raised its forecast for operating income. Iron Mountain's operating cash flow is $592 million, and its debt load of $3.16 billion dwarfs its cash in the bank of $271.8 million.

On Monday, Iron Mountain closed up 21 cents, or 0.7%, at $29.

Iron Mountain is also owned by the Vanguard 500 Index Fund, a three-star Morningstar-rated fund and managed by Michael H. Buek. The fund ranks in the top 40% of all funds in its category of large-blend funds for the last three years. Its portfolio also includes Chevron (CVX), with a short ratio of 1.7; International Business Machines (IBM), with a 2.6 short ratio; and General Electric (GE), with a 2.2 short ratio.

For more ideas, check out theBuvffet Short-Squeeze plays portfolio at Stockpickr.

At the time of publication, the author had no positions in stocks mentioned.