Europe's debt hangs over stocks (ext)

NEW YORK (CNNMoney) -- U.S. stocks closed little changed on Monday after a downgrade of Greece's credit rating tempered earlier investor enthusiasm for a series of corporate deals.

At the close, the Dow Jones industrial average (INDU) rose 1 point, or less than 0.1%, to end at 11,953; the S&P 500 (SPX) added less than a point to close at 1,272; and the Nasdaq Composite (COMP) fell 4 points, or 0.2%, to 2,640.

Stocks opened higher following a series of deals. But the gains were short lived after credit agency Standard & Poor's downgraded its rating on Greece to "CCC." S&P also kept its negative outlook on Greece.

The downgrade pressured the currency and commodity markets. Oil fell 2% to $97.30 a barrel. Silver prices slid more than 4%. And and gold dropped 1% to $1,515.60 an ounce.

"A couple months ago, the market would have overlooked a Greece downgrade," said David Levy, portfolio manager with Kenjol Capital Management. "But with this negative market sentiment, it's another reason to sell."

Stocks have taken a drubbing as of late, with concerns about the economy leaving investors battered and bruised.

With no economic data on tap for Monday's session, U.S. investors focused on a series of corporate deals announced before the opening bell.