Boston-based hedge fund manager Castine Capital Management LLC added 10 new financial stock positions during the first quarter, four of which were large enough to become top 20 investments, according to the firm's latest Form 13F.

Castine's largest initiation, a $13.4 million stake in Lewiston, Maine-based Northeast Bancorp, became its fifth-largest position overall at the end of March.

The hedge fund manager also revealed a new $9.5 million stake in Wayzata, Minn.-based TCF Financial Corp. and an $8.5 million position in Synovus Financial Corp. On Jan. 28, Detroit-based Chemical Financial Corp. announced that it would merge with TCF in a $3.55 billion transaction.

Established in 2003, Castine is principally owned by Paul Magidson, Ostrom Enders and Jonathan Cohen. The firm invests primarily in U.S. financial institutions.

Castine's total financial stock portfolio increased to $322.8 million as of March 31, up from $292.7 million at the end of December 2018.

During the first quarter, Castine boosted its holdings in Hartford, Conn.-based United Financial Bancorp Inc. by 79.3%, pushing its total investment in the company to $25.1 million, its single largest position.

Castine completely sold out of nine positions during the first quarter, including a $7.9 million stake in Chico, Calif.-based TriCo Bancshares, which had been a top 20 position at the end of 2018.

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