The backdrop for investing in the US stock market has gotten worse. The market bounce off the bottom anticipated an economy that hasn't been the bust that doomsayers predicted. The international backdrop now (sovereign debt concerns/euro stability) coupled with a high degree of complacency, however, is not a good combination. Liquidity driven rallies, with the accompanying high valuations, tend to end very badly.
Cash reserves are also very low, according to this Bloomberg piece from today.
S&P Rally Slowed by Fastest Cash Depletion Since 1991-Bloomberg News
Caveat emptor, which is Latin for watch your ass.