“UNSEEMLY” is the sort of adjective favoured by maiden aunts, if such things exist anymore. It’s certainly not a word you would imagine coming out of the X-rated mouth of Kenneth Langone, earthy co-founder of Home Depot and former director of the New York Stock Exchange (NYSE).

Yet last week “unseemly” was Langone’s mot juste for the NYSE’s plan to end its 212 years as a private club and become a public company. This is a historic moment on Wall Street and one that is igniting strong feelings. Linguistically, Langone can normally be relied upon to be more robust.

In 2003 Langone stepped down as a director of the NYSE, where he used to head the compensation committee. Langone’s friend and ally Dick Grasso, ex-NYSE chief executive, had previously resigned in disgrace over a $140m (€108.5m) pay deal Langone helped approve.

Eliot Spitzer, New York’s attorney general, is after Grasso to pay back some of that cash and also has Langone in his sights. Grasso, backed by Langone, sued the exchange, saying he was owed an additional $50m.

This is Langone’s now famous comment on the controversy in Fortune magazine last year: “They got the wrong f*****g guy. I’m nuts, I’m rich, and boy, do I love a fight. I’m going to make them s**t in their pants. When I get through with these f*****g captains of industry, they’re going to wish they were in a Cuisinart — at high speed. If Grasso gives back a f*****g nickel, I’ll never talk to him again.” My! Langone blames Hank Paulson, the chief executive of Goldman Sachs, and another former NYSE director for forcing out Grasso. Grasso was replaced by John Thain, a former Goldman golden boy. And so the conspiracy theory began: Grasso was ousted in a Goldman plot to take over the NYSE! The theory is frankly ridiculous and could only be believed by the sort of people who think it is okay to pay a public servant and quasi-regulator $140m (not including the disputed $50m) and for that money to be approved by the people he regulates.

But thanks to some shoddy footwork at Goldmans, the conspiracy theorists are off the ropes and punching back. Thain plans to take the NYSE public via a merger with electronic trader Archipelago Holdings. The NYSE might be the biggest, most powerful, exchange on earth but it is also an increasingly dated institution, still reliant on the “open outcry” system of trading featuring all those men in coloured jackets.

Rivals, like Nasdaq, long ago moved to electronic trading and have significantly lower costs. The Archipelago deal would help modernise the exchange, open up new areas of trading for the NYSE and provide currency for it to chase other mergers — it will surely now join the list of suitors for the London Stock Exchange.

Langone has been trying to stir up a counter bid. He has managed to recruit John Mack, a former CSFB boss, to co-ordinate what looked initially like a rival offer. Langone alone wouldn’t cause Thain much of a problem but with Mack in tow, a rival offer has to be a remote possibility. Wall Street is now crunching numbers, Thain is trying to smooth things over.

Most of the grown-ups on Wall Street think the Archipelago deal is a good idea. Mack and Thain are now talking and I’d say the deal will go through. But Thain is going to have to do some sort of penance. Given the recent history of the NYSE, Thain and Goldman have displayed a breathtaking arrogance in sorting this deal out between themselves. Unseemly is as unseemly does.