STEVE CHIOTAKIS: Nasdaq and InterContinental Exchange say together they put in an $11.3 billion offer to buy the New York Stock Exchange. That’s about 20 percent higher than another other from a German exchange.

Marketplace’s John Dimsdale reports whoever buys it, the NYSE takeover is gonna go under the microscope.

JOHN DIMSDALE: A Nasdaq/NYSE combination would bring together the two largest stock market operators in the U.S. Nasdaq touts the benefits from sharing technologies and streamlining their administration — all in the United State.

But Georges Ugeux, a former executive vice president of the New York Stock Exchange says regulators may not be convinced its best for competition.

GEORGES UGEUX: They will certainly scrutinize it deeply because on the cash market, they represent half the market and therefore they have a dominant position vis a vis all the other players.

But the stock exchange business is changing, says Adam Sussman at the equities research TABB Group. It’s becoming more competitive. And therefore he thinks a merger will stand up to regulatory review.

ADAM SUSSMAN: Just over last few years the securities and exchange commission has approved two new exchanges and the barriers to entry in terms of starting an exchange are surprisingly low.

Whichever deal works out for the NYSE will take a while. Shareholders aren’t expected to vote on a merger until this summer.

In Washington, I’m John Dimsdale for Marketplace.