likely just diversifying his holdings a bit. [On a shortish break, here.]
After all, his paycheck, and health care benefits, and pension payment (at eventual retirement) are all tied to the fortunes of only one company.
So spreading his assets out a little, putting some in other buckets, makes sense. And to do so, he had to liquidate some of his Merck investment. In sum, I'd read nothing in to this -- as to Merck's future or fortunes.
Now you know. [I'll likely break out at 6 PM EST here, to listen to the Ninth Circuit livestream at least for a bit. But being held captive by clients until then, today. And flying back in the evening tomorrow, now. . . Smile. . .]