Manchester United have signed the biggest shirt sponsorship deal in the history of soccer after agreeing a US$120 million partnership with American financial giant Aon Corp.

The four-year deal comfortably eclipses United’s previous shirt sponsorship, with AIG, and is almost double the amount earned by the likes of Chelsea and AC Milan. Only Bayern Munich’s deal with T-Home approaches the amount, at US$25 million per year.

Chelsea’s sponsor, electronics giant Samsung, had been one of the names linked with United. The company pays Chelsea US$17.6 million per year for its shirt sponsorship, while AC Milan earns just under that from its partnership with Bwin. Bwin also sponsors Spanish giants Real Madrid to the tune of US$21 million per year. German club Schalke 04, meanwhile, makes US$16.7 million from its deal with Gazprom.

United, Premier League champions for the last three years, will be sponsored by Aon from May 2010, when the AIG deal expires. The team’s title triumph in May saw it draw level with Liverpool at the top of the record books for English championship wins. The two northern clubs now have 18 titles apiece.

Aon is the world’s largest insurance broker, with 37,000 employees across the world, 5,400 of them in the UK. The Times newspaper reported of the company: ‘The recession has hit it hard, sending profits in the fourth quarter tumbling to US$10million from US$207m at the same time a year before and triggering a cost cutting spree in which it warned that “no stone is being left unturned” as it seeks to streamline its operations.‘