Argonaut received an offer from a Bermuda firm.

In an offer valued at $380.8 million, Clarendon Group Ltd., a privately held Bermuda-based firm, proposed acquiring Argonaut Group Inc. for $37 a share. Clarendon already owns about 540,000 of the 11.7 million common shares of the Los Angeles-based insurance holding company, which primarily sells and services worker’s compensation insurance. The company was formed Oct. 1 as a result of a corporate spinoff by Teledyne, a Los Angeles conglomerate.