By Laura McGuire Barratt Developments will update investors on its half-year trading performance this Wednesday, with hopes that cooling mortgage rates will boost its balance sheet. Shares at the FTSE 100 developer are trading higher than a year ago and up by a third from their autumn nadir, despite flagging multiple times that a slowdown in house purchasing was eating its bottom line. Barratt has also trimmed its full-year dividend to 33.7p from 36.9p a share in fiscal 2023 and brought its share buyback programmes to a close. Before Christmas, chief David Thomas said the outlook for the year …