(Updates with the stock move in the headline and the second paragraph.)

Acadia Pharmaceuticals (ACAD) is set to join the S&P SmallCap 600 index on Jan. 3, replacing Independent Bank (IBTX), S&P Dow Jones Indices said late Monday.

Acadia shares were up 12% in recent Tuesday trading.

Independent Bank is being acquired by SouthState (SSB) in a deal expected to close soon, the index operator said.

Price: 18.69, Change: +2.00, Percent Change: +11.98