As Europe stemmed fears of contagion from Greece’s default by arranging voluntary rollovers of private bonds and the United States hammers out a deal over its debt ceiling, stocks tentatively moved up in Tuesday trading.

The “wild card,” says BlackRock’s Bob Doll, is a substantial downgrade of U.S. debt from one or more of the ratings agencies, which would push any investors required to hold AAA debt to sell Treasuries.

Doll expects the U.S. to take significant steps to reassure the agencies: “We believe that deep spending cuts are coming -- it’s just a matter of Washington coming to an agreement over which cuts, how much and when,” Doll says.

And despite all these risks, Doll doesn’t see signs of recession.

With about 25% of company results posted for the second quarter, most have exceeded estimates and have improved sales. Industrial production and consumption are also rebounding, leading BlackRock to project stronger economic growth in the second half of 2011.

A good deal of cash is still on the sidelines, and should return to stocks, he said.