Buyers busy in 10-year Treasury auction

If you want to know why the stock market trimmed its losses this afternoon, look to the 10-year Treasury auction.

The Treasury auctioned off $21 billion in 10-year Treasury notes at a yield of 3.9%. The yield was the highest since June, but it was better than the 3.948% average projected by Bloomberg News. As a result, the major indexes saw their losses on the day substantially shaved.

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There was good news in the demand, and that's what cheered investors.

The bid-to-cover ratio was 3.72-to-1. That means there were $3.72 in bids for every dollar auctioned. That was the biggest ratio ever and well above the 3.06 ratio of the last four auctions.

Indirect bidders, a group that includes foreign central banks, bought 43.1%, versus 36.6% of the last four on average.

The Dow Jones industrials ($INDU) had been down as many as 73 points in the morning. The blue chips were still down as many as 40 points just before the auction. And when the results were disclosed, the Dow's loss was trimmed immediately to about 13 points.

At 1:55 p.m. ET, the Dow was down 29 points to 10,941. The Standard & Poor's 500 Index ($INX) was off 2 points to 1,188. The Nasdaq Composite Index ($COMPX) was up 2 points to 2,439.

The auction was very closely watched because auctions in recent weeks had suggested waning demand for U.S. securities.

Helping today's auction was a new round of uncertainty about the finances of Greece. That pushed up yields on Greek bonds well above 7% and pushed the euro lower against the dollar.