Stocks in seesaw mode

NEW YORK (CNNMoney.com) -- Stocks struggled for direction Monday morning as investors weighed a rash of merger and acquisition news with the latest worries about the subprime mortgage lenders.

The Dow Jones industrial average (down 5.20 to 12,271.12, Charts) and the broader S&P 500 (down 2.67 to 1,400.18, Charts) index both inched just below unchanged around 90 minutes into the session, while the tech-heavy Nasdaq (up 1.41 to 2,388.96, Charts) composite was little changed.

Stocks were skittish Friday but managed to end the week higher, as investors recovered a bit from the previous week's big selloff.

Monday was again volatile, as investors weighed competing influences at the start of a busy week for economic news. Reports due later in the week include retail sales, producer and consumer prices and manufacturing.

Monday brought a number of merger announcements.

Schering Plough (up $0.03 to $23.88, Charts) is buying Akzo Nobel's drug unit for $14.4 billion in cash.

Dollar General (up $4.41 to $21.19, Charts) has agreed to be taken private by Kohlberg Kravis Roberts & Co. in a $7.3 billion cash and debt deal.

UnitedHealth Group (up $0.26 to $53.26, Charts) said it was buying Sierra Health Services for $2.6 billion in cash.

In addition, Ford Motor (down $0.06 to $7.87, Charts) said it was selling its luxury Aston Martin line for $925 million.

However, the deal news was countered by new worries about subprime mortgage lenders.

New Century Financial (Charts) said its lenders have cut off its financing, in the latest blow to the mortgage lender to people with less than top credit. The New York Stock Exchange delayed opening trading for the stock and later announced that it was considering suspending trading.

In addition, Countrywide Financial (down $0.82 to $35.28, Charts) said its expects some short-term earnings volatility due to events in the subprime mortgage lending market. Shares slumped about 3 percent.

U.S. light crude oil for April delivery fell $1.37 to $58.69 a barrel on the New York Mercantile Exchange.

COMEX gold for April delivery fell $4.20 to $647.80 an ounce.

Treasury prices rose, lowering the yield on the 10-year note to 4.55 percent from 4.58 percent late Friday. Treasury prices and yields move in opposite directions.

In currency trading, the dollar fell versus the yen and the euro.

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