Shares of CYS Investments Inc. shot up 10.1% in premarket trade Thursday, after the agency mortgage real estate investment trust (REIT) said it agreed to be acquired by fellow REIT Two Harbors Investment Corp. , in a deal that would value CYS at about $1.21 billion. Two Harbors shares slumped 1.5% ahead of the open. Under terms of the deal, CYS shareholders will receive $7.79 of combined cash and Two Harbors stock for each CYS share they own, representing an 17.7% premium to Wednesday's closing price of $6.62.