According to WSJ, KCG Holdings (KCG) approached by Virtu Financial (VIRT)

Trading firm Virtu Financial (VIRT) has made a bid to acquire rival KCG Holdings (KCG) which could help shore up businesses that have been struggling with damped market volatility.

Update(s):

April 20, 2017: High-speed trading firm Virtu Financial Inc. (VIRT) reached a deal to acquire rival KCG Holdings Inc. (KCG) for $1.4 billion in cash, a tie-up that would create an electronic trading giant responsible for around one-fifth of volume in U.S. equities.