NEW YORK (Reuters) - Nasdaq Inc NDAQ.O said it canceled trades that spanned a two-minute period before the opening bell on Wednesday which affected about 50 securities.

The exchange initially said it was investigating "potentially erroneous transactions" that occurred between 9:23 a.m. ET (1323 GMT) and 9:25 a.m. ET (1325 GMT) and included names such as Michaels Companies MIK.O, Mercury General Corp MCY.N and Mohawk Industries MHK.N.

Within the hour, Nasdaq announced that it had determined to cancel all of the trades within the timeframe that were executed at 30% above or below the consolidated closing price.