Legendary investor Warren Buffett said he has no idea what the Federal Reserve will do with interest rates next week, but he doesn't base his investment decisions on the Fed. Buffett spoke to TheStreet ahead of a charity luncheon in New York. Buffett said he's interested to hear about what's going on in China from the auction winner, Chinese businessman Zhu Ye. China has roiled markets in the last few weeks, but Buffett said investors should buy an index fund and not worry about day to day stock moves. Buffett recently made his biggest acquisition ever, with a $37-billion purchase of Precision Castparts, but that doesn't mean he's not looking for more companies to buy. ‘I will be looking every day I promise you that. And if I find something that makes sense, I will move,’ he said. Buffett added his cash position is higher than he’d like it to be. Buffett, who recently turned 85, said he did ‘nothing special’ to celebrate his birthday . ‘I just took a deep breath and found out I was still alive at 85 and decided I’m just going to keep doing that every day for a long time,’ said Buffett.