Sony got a stake in Olympus' future when it made a $645 million investment into the troubled camera firm last September, getting a board representative and a controlling share of a medical imaging project. As of this weekend, however, the foot is that much further in the door: it's now Olympus' largest shareholder. A share transfer promised alongside the investment, and officially completed on the 22nd, has boosted Sony's stake from 4.7 percent to just under 11.5 percent. The share switch doesn't give Sony enough influence to dictate Olympus' day-to-day affairs, but Sony won't have to do as much to rally support if it wants action. Olympus isn't in the best position to kick such a large investor to the curb, either. We'd expect the company to at least listen more closely to what its major funding source has to say.