Buffett has consistently bought shares at this level for two years, but now he's stopped.Warren Buffett is currently sitting on more cash than he has good ideas to invest in. Berkshire Hathaway's (BRK.A -0.34%) (BRK.B -0.96%) cash and Treasury holdings could exceed $300 billion by the end of the third quarter. That's driven by Buffett's recent decisions to sell stocks from Berkshire's equity portfolio without reinvesting the funds into new holdings. Buffett's sold more stocks than he bought in each of the l ...