Twitter has lost several of its top executives in the past few months, and its troubles deepened as two more executives quit the company on Tuesday. The micro-blogging service has now lost Chief Technology Officer Adam Messinger and Vice President of Product Josh McFarland.

In a tweet, Messinger said he need some time off, while McFarland quit the company to join venture capital firm Greylock Ventures as a general partner next year. The departures of these executives come on the heels of several other upper-management exits, including former COO Adam Bain, who quit last month. The company replaced him with Anthony Noto.

In a reply to Messinger’s resignationtweet, CEO and co-founder Jack Dorsey said, “We’ve shown our strategy is having a direct and positive impact on our audience growth and engagement, and we’re executing better and faster every day. I’ll be working even closer with our engineering and design teams to ensure we continue to be the fastest and best service to show what’s happening in the world.”