S&P 500 Leaders & Laggards: Alcoa, WaMu

Alcoa Inc. recorded the largest gain on the Standard & Poor's 500 on Monday, helping lift the index to a higher close after wavering during the session.

The S&P 500 added 1.08 to 1,361.76, as crude prices dipped, but only after Friday's surge to a new record. The broad market index moved back and forth between positive and negative territory during the session.

Aluminum maker Alcoa rose $2.95, or 7.5 percent, to $42.17 on heavy volume. A report in Barron's over the weekend discussed the possibility of a takeover of the company.

Oil and gas driller Ensco International Inc. advanced $4.87, or 6.6 percent, to $79.27.

Independent oil and gas company Apache Corp. gained $8.09, or 6 percent, to $141.99.

On the losing side, financial stocks took the biggest hit, after Lehman Brothers Holdings Inc. forecast a second-quarter loss and Wall Street worried about further losses among others in the sector due to the mortgage and credit crisis.

Washington Mutual Inc. dropped $1.28, or 17 percent, to $6.25. A UBS analyst predicted additional credit losses for the bank through 2011. During the session, shares hit $6.05, their lowest point since 1992.

Bond insurer Ambac Financial Group Inc. lost 24 cents, or 10.2 percent, to $2.11. The stock hit an all-time low of $2.02 during the session. Fellow bond insurer, MBIA Inc., declined 55 cents, or 10.1 percent, to $4.89, after hitting $4.78, their lowest point since early 1988. Standard & Poor's Ratings Services slashed ratings on 799 classes of asset-backed securities backed by MBIA and Ambac.