NEW YORK — Stocks ended a wobbly session with a mixed performance Wednesday as concerns about the financial sector eroded enthusiasm over a continued decline in oil prices and a report indicating modest growth in the service economy.
The worries about financial companies flared after Moody's Investors Service warned that it might downgrade the ratings on bond insurers Ambac Financial Group and MBIA Insurance.
Some investors looking to sidestep the troubled sector moved into technology stocks, giving the Nasdaq composite index the biggest advance of the major indexes.
After two days of sharp declines, in which the Dow Jones industrials lost 235 points, the slide in oil appeared at times to lift market sentiment.
Also boosting stocks, the Institute for Supply Management's service sector index edged down to 51.7 in May from 52. Any level above 50 signals economic expansion, so the gauge's latest reading bolsters the case that the economy, though behaving erratically, isn't in a steady downturn.
But recently revived credit concerns sent an index of the financial stocks in the Standard & Poor's 500 down 0.8%. The gauge has fallen 3.9% in the last four sessions.
"Financials again are the lead story," said Neil Massa, senior trader at MFC Global Investment Management in Boston. "The market is not going to recover until the financials do."
The Dow Jones industrial average fell 12.37 points, or 0.1%, to 12,390.48.
Broader indexes were mixed. The Standard & Poor's 500 index inched 0.45 of a point lower to 1,377.20, while the Nasdaq gained 22.66 points, or 0.9%, to 2,503.14.
The Russell 2,000 index of smaller-company stocks rose 4.71 points, or 0.6%, to 743.71.
Declining issues outnumbered advancers by about 6 to 5 on the New York Stock Exchange. Treasury bond yields rose, with the benchmark 10-year Treasury note climbing to 3.98% from 3.9% late Tuesday.
Oil futures sank $2.01 to settle at $122.30 a barrel on the New York Mercantile Exchange after the Energy Department reported that demand for gasoline receded last week and fuel inventories jumped more than expected.
The dollar was mixed against other major currencies, while gold prices fell.
The latest evidence of uneasiness about the financial sector came from Moody's announcement that it was considering downgrades of Ambac and MBIA. Ambac tumbled 51 cents, or 17%, to $2.49, while MBIA sank $1.06, or 15.9%, to $5.63.
