The investment group Castine Capital Management has been sharply reducing its ownership stake in First California Financial Group (FCAL) even as it has been pressuring the company to sell itself.

Boston-based Castine disclosed in a Securities and Exchange Commission filing Monday that it has sold off roughly half its stake in the $2 billion-asset First California since late January and it now owns 2.6% of its outstanding shares.

Castine was one of two large shareholders in January that sent letters to First California's board expressing frustration with the company's strategic growth plan and urging it to find a buyer. PacWest Bancorp (PACW) in Los Angeles offered to buy Westlake Village-based First California earlier this month for $212 million, but the bid turned hostile last week when First California's board said it would not accept the offer under its current terms.

It is unclear why Castine began unloading its shares so soon after it began agitating for a sale. The firm gave no explanation in its SEC filing and a call to managing member Paul Magidson Monday was not returned.

Still, Castine has clearly benefitted from the run-up in First California's shares that began when Castine and other investors began applying the pressure. The stock climbed 28% in January, 26% in March and is up more than 100% for the year, to $6.97 midday Monday.

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