The Glasgow-born frontman came through the youth ranks at Bolton after joining the Trotters from Celtic in 2007 and made his Wanderers debut at the age of 20 in a League Cup tie in August 2011 as a substitute in a 2-1 win against Macclesfield, O'Halloran's only other senior appearance for Bolton coming five months later when, again versus Macclesfield at home, he made another substitute appearance in a 2-0 FA Cup win, O'Halloran failing to find the net in either short spell on the pitch.
In late February this year the 6'2 forward signed a three and a half year extension to his contract at the Reebok Stadium, which takes him up to the summer of 2015, before he went out on loan to Sheffield United in late March to the end of the season. O'Halloran going on to make one start and seven substitute appearances and score no goals for the Blades in his temporary spell at Bramall Lane, one of the those games from the bench being in the 8-7 penalty shootout defeat, in which he scored his spot-kick, against Huddersfield Town in the League One play-off final at Wembley.
Internationally meanwhile O'Halloran has played four times at Scotland under-17 level, while scoring one goal away to Malta, once at under-19 level and then twice at under-21 level, the most recent of those seven caps coming two and a half weeks ago in a 1-0 friendly defeat at home to Belgium. Michael hasn't been selected for the under-21s in their final two European Championship Qualifiers on the 6th and 10th of September though, so he will be available for Carlisle then, as well being eligible for both the Capital One Cup and Johnstone's Paint Trophy ties against Tottenham Hotspur and Preston North End respectively.
First Team Transfers 2012-13 : Click here