The two main stock markets in the US have acquired smaller rivals to take advantage of their electronic trading technologies.
The New York Stock Exchange plans to merge with Archipelago Holdings, an all-electronic exchange founded eight years ago. And Nasdaq is buying Inet, Instinet Group's e-trading platform for $934m (£518m).
Both deals await regulatory and shareholder approval.
The New York Stock Exchange said the combined operation would make hundreds of millions of dollars in cost savings. The Archipelago electronic trading system will work in parallel with the New York stock market's trading floor system.