About ten year ago ASUS spun off its entry-level motherboard production into a new brand named ASRock. Over the years, ASRock gained quite a lot of marketshare and they're now the third biggest motherboard shipper, with 8 million units anticipated to ship this year. Former parent company ASUS is still number one with 23.2 million units estimated to ship in 2012, and Gigabyte has a second place with 19 million units.
A report by SemiAccurate claims ASUS is now worried about ASRock getting too large, and that the company has made a bid for ASRock's motherboard division. According to the article, ASRock's parent company Pegatron, which is basically ASUS' former manufacturing arm, is essentially fine with the terms.
SemiAccurate adds that if the buyout goes through, ASUS will become by far the largest motherboard maker, and speculates that the already unhealthy industry would likely collapse into two players before people realized what happened.