By Jack Mendel The competition watchdog has launched a formal investigation into the £2.5bn tie-up between Barratt and rival housebuilder Redrow, the agency announced this morning. The Competition and Markets Authority (CMA) said it will decide on whether to refer the housebuilding merger for a phase two investigation by early August. This comes after the CMA said in March it was looking into the merger over fears it may damage competition. The CMA said it was unlikely to send the proposed merger for phase two probe if it does not receive more submissions on the deal. The newly merged group wo…