The Dow Jones industrial average rose 219 points, or 1.74%, to 12,821. The Standard & Poor's 500 Index gained 25 points, or 1.95%, to 1,355. The Nasdaq Composite Index climbed 63 points, or 2.23%, to 2,912.
European markets also rose sharply, with the Stoxx Europe 600 up 2.7%, as Spanish and Italian government bond yields fell, after European leaders said they would speed plans to create a single supervisor for the euro zone's banks, and agreed on measures aimed at stabilizing the bonds markets.
Risk sentiment took a 180-degree turn after the EU Summit. Gold rose more than 3% to above $1,598 an ounce, while crude-oil futures gained over 5% to $82.15 a barrel.