The technology-heavy Nasdaq said on Monday it would buy eSpeed, the electronic trading platform for US treasuries.

Nasdaq will pay $750 million to BGC Partners for the platform. The deal is expected to be completed by the summer.

Robert Greifeld, Nasdaq’s chief executive officer, said the move will diversify the shares index “in a measured way.”

The ratings agency Moody’s warned immediately that it could cut Nasdaq’s credit rating following the eSpeed deal. The takeover will add about $1 billion to Nasdaq’s debt burden, Moody’s said.