Solectron, which owned 23.5% of ECS, sold the remaining 2.15% to an undiclosed group.
ECS officials said the deal shouldn't have negative repercussions for ECS, which doesn't distribute Solectron products.
In a press statement issued jointly by ECS and ST Electronics, the companies said the investment isn't expected to have a material impact on earnings in 2004.
ST Electronics designs and develops electronics systems mainly for industrial use. ECS provides IT services and sells software and hardware.