This morning (Oct. 17), billionaire investor Warren Buffett has an op-ed in the New York Times saying he is buying stock. The statement is credited with turning a down market into an up market early today (but there is no telling what will happen the rest of the day, particularly the last hour.) Buffett is probably the world's greatest investor, but as he readily admits, he has been wrong. His San Diego experiences are an example. In 1987, US Air bought the airline from San Diego's Pacific Southwest Airline, or PSA. The rest of PSA, consisting mainly of airplane leasing operations, became PS Group Holdings. Buffett's Berkshire Hathway put $358 million into US Air in 1990. By 1995, it was worth $86 million, according to San Diegan Janet Lowe's book on Buffett, "Damn Right!" In 1998, Berkshire got its money back, but Buffett was humbled by the adventure. Berkshire bought 11 percent of PS Group and in 1990 got permission to buy up to 22.5 percent as the stock moved above $36 on the news. But PS Group foundered. Its attempt to put together a group of travel agencies failed. A recycling experimental investment didn't work out. In 1999, PS Group was acquired for $12 a share.