Opko Health (OPK) announced that it has signed an agreement to acquire Transition Therapeutics (TTHI) in a all stock transaction. OPK is acquiring TTHI for 6.4 million shares of its common stock. Based on on the average price of OPK shares over the five days preceding the signing of the contract, the transaction is valued at ~$60M or $1.55 per TTHI share. The deal is expected to close in the second half of this year.