S&P 500 Leaders and Laggards: SAF ABK

The S&P 500 added 3.99 points to close at 1,379.93.

Safeco surged $20.71, or 45.8 percent, to $65.94. Earlier in the session, Liberty Mutual offered to pay $68.25 per share for the company, a deal that would create the fifth-largest property insurer.

The deal is valued at $6.12 billion.

Broadcom Corp. gained $3.84, or 16.3 percent, to $27.39 after the chip maker posted a first-quarter profit and next-quarter outlook that beat Wall Street estimates.

Molex Inc. advanced $3.77, or 15.2 percent, to $28.56. Late Tuesday, the electrical parts maker posted fiscal third-quarter earnings that beat analyst expectations.

Among the losing shares, Ambac Financial Group Inc. plummeted $2.57, or 42.6 percent, to $3.46 after hitting a fresh annual low of $3.08 earlier in the session. The bond insurer swung to a $1.66 billion loss in the first quarter on turmoil in the bond market, sending shares of several other insurers lower.

Fellow bond insurer MBIA shed $4.49, or 33.8 percent, to $8.79.

MGIC Investment Corp., a mortgage insurer, lost $1.84, or 13.8 percent, to $11.51.