On Friday a full-page New York Times advertisement warned investors that the animal rights movement has grown dangerous enough to cow the world’s largest financial marketplace into submission. The ad features a masked terrorist under the words “I Control Wall Street.” A guessing-game has developed (reaching as far away as a wire service in Italy) over the source of the ad, whose only signature is an Internet website. But whoever is responsible, they plainly got it right.

The “NYSE Hostage” website tells the story of an animal rights group called Stop Huntingdon Animal Cruelty (SHAC), which is hell-bent on destroying a medical research firm that uses lab animals to search for cancer and AIDS therapies. In September 2005, SHAC militants, six of whose leaders were later convicted on federal terrorism charges, succeeded in forcing the New York Stock Exchange to abandon its plans to list the research firm on the Big Board. How this was accomplished isn’t entirely clear, but it appears to have involved hundreds of threatening e-mails and phone calls directed at stock exchange executives and employees.

The Exchange now has considerable egg on its face, but the larger point is that modern anti-everything activist groups are highly adaptable. They learn from one another. And if threatening the NYSE brings a desired result to animal-rights miscreants, what will stop other groups — whether motivated by animal “rights” or some parallel fervor — from adopting the same tactics?

Yesterday CNBC online editor Charlie Gasparino indicated that the Street has taken notice. “The New York Stock Exchange caving,” he said, “is really — I mean they set a horrendous precedent. I was at the luncheon club for the closing on Friday. This is the esteemed luncheon club where all the members [have] been. And let me tell you something. This is all they could talk about.”

We’ve already seen People for the Ethical Treatment of Animals (PETA) adopting some of SHAC’s controversial tactics, including intimidating protests at their targets’ homes and places of worship. How long will it be until other special-interest protest factions take the same kind of initiative? The “NYSE Hostage” website speculates that labor unions, environmental groups, and “corporate accountability” groups might give the Exchange a New York-sized headache the next time the cause du jour involves a publicly traded company. Time will tell.