What Buffett means to Berkshire

What Buffett means to Berkshire: FORTUNE -- Warren Buffett, it appears, is worth less than he used to be. Shares of Buffett's Berkshire Hathaway (BRKA) fell slightly, down about 1%, on Wednesday, a day after the company's legendary CEO announced he has Stage 1 prostate cancer. Buffett said his condition is "not remotely life-threatening" and would barely slow him down. (He won't be able to travel, while getting radiation treatment, for two months starting in mid-July.) Surely, part of the small drop has to do with the fact that few think Buffett is going anywhere soon. Nonetheless, the muted reaction of Berkshire's shares raise the question of just what investors think the 81-year-old CEO is worth to the company and its shares. The answer might be a lot less than they used to.