Argonaut Group Inc. said it hired Credit Suisse First Boston to examine merger opportunities. The Los Angeles-based company provides workers' compensation insurance and other forms of commercial coverage. Its shares rose 11% in the last 12 months, compared with a 35% gain in the Standard & Poor's index of property and casualty insurers. Chairman Henry Singleton said Argonaut's directors decided "to explore the alternatives available to enhance shareholder value." Shares rose $3.19 to close at $36.24 on Nasdaq.