America is getting a new stock exchange from the most prominent critics of high-frequency trading.

After months of delays and a brutal lobbying battle that divided Wall Street, the IEX Group won approval Friday from the Securities and Exchange Commission to become the nation’s 13th official stock exchange.

IEX is run by the people at the center of the Michael Lewis book “Flash Boys: A Wall Street Revolt,” which profiles the early efforts of the IEX team to create a trading exchange that would be somewhat shielded from high-frequency traders.

Other exchanges and trading firms had urged the SEC to reject IEX’s application.

IEX opponents, including the other stock exchanges, have argued that the structure of the new exchange will add unnecessary complexities to an already complex market and potentially hurt small investors.

But the three SEC commissioners all voted Friday to approve the IEX exchange, with one commissioner, Michael Piwowar, a Republican, dissenting on a few points.

“Today’s actions promote competition and innovation, which our equity markets depend on to continue to deliver robust, efficient service to both retail and institutional investors,” Mary Jo White, the SEC chairwoman, said in a statement.

The most novel and controversial feature of the IEX exchange is a speed bump that would slow trading slightly to throw off traders that rely only on speed.

The speed bump slows trades by only 350 microseconds — or millionths of a second — but that is an eternity in a stock exchange universe in which computers can buy and sell stocks in nanoseconds — or billionths of a second.

Nasdaq and other exchanges have said the IEX’s speed bump would violate rules mandating that exchanges make their prices available to all parties at the same time.

In a statement, the SEC said the commissioners had “determined that a small delay will not prevent investors from accessing stock prices in a fair and efficient manner.”

IEX has already been operating as a private trading pool and has recently been attracting about 1.6 percent of all daily trading volume.