Takeover target Adelaide Brighton Ltd said today that its major shareholder, UK-listed RMC Group plc, had sold another 20 per cent of its stake in Adelaide Brighton at $1.40 per share.  Adelaide Brighton, which produces lime and cement, said it had been informed that the shares had been placed with institutional investors.  It believed that RMC Group plc now held about 14.9 per cent of Adelaide Brighton.  Adelaide Brighton is subject to an A$840m takeover bid announced last week by building products firm Boral Ltd, following RMC's decision to sell Boral 107.8 million shares in Adelaide Brighton.  Boral is offering $1.55 per share for Adelaide Brighton, with the offer subject to approval by the Australian Competition and Consumer Commission (ACCC) and a 90 per cent acceptance condition. RMC had held 55 per cent of Adelaide Brighton before the sale of the shares to Boral.  RMC has also announced its intention to sell the remainder of its stake in Adelaide Brighton.