SunGard is bidding 80p per share and will take on Guardian iT's £11m debt burden. The deal comes two months after Guardian iT announced it was in talks with a buyer.
SunGard customers in the UK should benefit from plans to continue developing Guardian's Heathrow facility into a technology hub that will be "the largest dedicated information availability services facility in Europe".
Cristóbal Conde, president and chief operating officer of SunGard, said: "This acquisition strengthens our global capability, allowing us to provide our customers with enhanced information availability services and access to a greater number of facilities.
"Guardian and SunGard both have extremely capable staff that will work together to support our combined customer base."
Before the takeover, SunGard boasted more than 8,000 clients in North America and Europe with access to 60 facilities containing two million square feet of hardened space and 10,000 end user positions.
In a financial statement to accompany the SunGard takeover, Guardian IT blamed its financial plight on reduced spending by customers and the deferral of purchasing decisions into 2002. Despite 11 September, Guardian's business continuity division was hit hard.
"This division proved to be much less resilient than had been expected and order intake in the last quarter of 2001 fell well short of expectations, leaving full-year turnover substantially down on budget," the company noted.