Sure, there are reasons for optimism. But there may be too many risks to justify jumping into U.S. stocks at these levels. The outperformance of many international markets could continue.

Wall Street is on track to open with modest losses Friday, though the retreat before the bell is not enough to negate a broad rebound in market s this week. Futures for the S&P 500 fell 0.1%, while futures for the Dow Jones Industrial Average lost 0.