Liberty Mutual agrees to buy Safeco for $6.12 billion

Liberty Mutual, a privately owned insurer based in Boston, has offered $68.25 per share for Safeco, a 51 percent premium to Tuesday's close.

Safeco, based in Seattle, sells $5.9 billion in insurance policies a year, while Liberty books annual premiums of more than $20 billion.

Both boards have approved the deal, and the sale is expected to close by the end of the third quarter pending shareholder and regulatory approval.