(Bloomberg View) —Congratulations to exchange operatorBATS Global Markets, which successfullylisted itself on its own BZX Exchange on Friday andtraded up 21 percent on its debut, giving it a 50 percent success rate for initial public offerings on its platform. (“The exchange operators biggest feat was avoiding technical problems like those that doomed its first attempt to go public four years ago.”)

Elsewherein exchange debuts, the Securities and Exchange Commission continues to ponder IEX’s controversial application to become a public stock exchange. I sympathize with the SECin its indecision– the controversy is real and central to equity market structure, and the positions are heartfelt — but I am not sure that dragging the process out for so long has been good for anyone. The SEC’s proposal to settle the controversy over IEX’s 350-microsecond speed bump byallowing any exchange to use a uniform delay of up to one millisecond, which looked likea quick blunt fair solution, has not gone over well:

We are concerned that the SECs proposal would likely introduce significant unnecessary market complexities and create significant risks for investors, wrote William Stephenson, global head of trading at Franklin Templeton Investments, which manages $742bn of assets. We worry that the SECs proposal could create future unknown conflicts that simply reside in a one millisecond world.

That seems right? One model you could have for the IEX application is:

IEX are nice. They want to do a new weird thing that will complicate market structure. Basically every problem in equity market structure comes from introducing new weird things that high-frequency trading firms know how to exploit but that regular long-term investors don’t fully understand. But IEXwill be nice about it. But once you let them do it, you have to let everyone do it. No one else is nice.

I am not sure that model is accurate in every detail, butI suspect it helps explain Franklin Templeton’s worries. Here is a comment letter from the Committee on Capital Markets Regulation to similar effect. On the other hand, here is a comment letter from Eric Budish, the leading proponent of “batch auctions” in equity markets, arguing that allowing a1 millisecond “de minimis” delaywould allow exchanges to experiment with batch-auction-like mechanisms to cut down on latency arbitrage. And here is a comment letter from high-speed trading firm Hudson River Trading that is sort of eye-opening:

In the fourth quarter of 2015, over 13% of displayed orders in large stocks are canceled within one millisecond. Since the sender of an order knows it is outstanding immediately upon sending, it may determine to cancel the order at any point after sending it. However, market participants that may want to trade with the order must be informed of the order on a market data feed and respond to it. To the extent that a market with similar order cancelation patterns implemented a one millisecond delay, over 13% of quotes in large stocks would not be available for execution when a firm receives the order on a market data feed and responds to it. In addition, the Commissions data show that over 9% of displayed orders in large stocks are executed within one millisecond. Given that over 20% of orders are either executed or canceled during the first millisecond they were displayed, it seems likely that a one millisecond delay would have a material impact on a participants ability to access the quotations.

“One millisecond is not de minimis in any context except from the perspective of a human trader,” writes Hudson River, and it is useful to remember that in the stock market the “human trader” isa weird interloperand hardly worth worrying about.