Sean Simon and Michael Singer have a problem on their hands. As co-presidents of Jericho, New York–based Ivy Asset Management Corp., they run one of the alternative investment industry’s oldest, largest and at times most innovative fund-of-hedge-funds firms. From 2000 to 2004, Ivy grew its assets on average by more than 50 percent a year, capitalizing on the surge in investors’ interest in hedge funds following the bursting of the stock market bubble.