Perot took over CVS's Woonsocket, R.I., data center, then expanded and rebranded it the Northeast Technology Center to serve multiple New England healthcare companies. It was an IT services win-win. But times changed, and so did the two outsourcing partners.

In 2007, CVS acquired pharmacy benefits management company Caremark for $26.5 billion and, along with the deal, a whole new business-to-business customer base and a host of IT assets, including another data center in Scottsdale, Ariz. The merger created "a very, very different company," says Stuart McGuigan, who joined CVS Caremark as SVP and CIO during the integration in 2008. "After [that merger], the market strategy of the company and the role of IT was different." (As of April, the Federal Trade Commission and 24 state attorneys general were investigating whether CVS Caremark had engaged in anti-competitive behavior.)

IT needed to be more agile to serve the needs of new customers demanding quick integration, such as GE, AT&T and Blue Cross Blue Shield. "We had to think about technology interoperations," McGuigan says. "The whole premise of our sourcing strategy changed."

From a scale perspective, outsourcing still made sense. But McGuigan had other considerations to weigh. He explored having Perot work in tandem with the insourced Caremark data center, but it wasn't ideal. "Even with the best of processes and intentions, you don't have the same agility when things are outsourced," he says.

Multimillion-dollar outsourcing deals aren't easily scrapped, but opportunity knocked in the form of Dell's purchase of Perot in 2009. CVS's contract stated that in the event of a change in vendor control, the agreement could be ended with reduced termination fees. CVS and Perot struck a deal allowing Perot to pay to keep one client on premise while moving all its other customers out. McGuigan's leadership team spent six months on the transition. "The first two months were heads-down detailed planning," says McGuigan, who went over everything from process requirements to HR issues. The switch over was complete last June 1.