 To commence at the start of the 2006–07 season, American insurance corporation AIG agreed a four-year £56.5 million deal which in September 2006 became the most valuable in the world.At the beginning of the 2010–11 season, American reinsurance company Aon became the club's principal sponsor in a four-year deal reputed to be worth approximately £80 million, making it the most lucrative shirt sponsorship deal in football history.Manchester United announced their first training kit sponsor in August 2011, agreeing a four-year deal with DHL reported to be worth £40 million; it is believed to be the first instance of training kit sponsorship in English football.