Perhaps they spoke too soon. On Monday the New York Times editorialists confidently declared, “The prospect of higher taxes did not dent, in the least, the initial public offering on Friday of the Blackstone Group, the giant public equity firm.” This judgment, intended to bolster the Times’ argument for tax increases, was made on the basis of exactly one day’s trading in the stock. And it was open to question; Blackstone stock’s first-day “pop” “was not especially impressive,” a Forbes article said, comparing Blackstone’s 13.1% first-day increase to the 67.6% initial rise in Fortress Investment Group and the 33% opening-day increase in Goldman Sachs stock.

But just how mistaken the Times editorialists were became more clear on the day the Times editorial appeared. Blackstone stock plunged 7.5%. Tuesday, it dropped another 5.2%, and yesterday it fell another 2.7% to $29.92 a share, well below the initial offering price. In other words, in the three days since the Times editorialists pronounced that the prospect of higher taxes had not dented “in the least” Blackstone’s debut, the company lost $5.5 billion in market capitalization, about 14% of its value.

Now, there are plenty of explanations being bandied about for the slide in Blackstone’s stock price. The stock market as a whole has been sagging, though not by as much as Blackstone. Some feel that the private equity market has peaked. And it’s possible Blackstone will go on to soar to new highs, particularly if the threat from Washington to increase taxes is defeated. But surely the looming specter of a huge tax increase has something to do with the dent that, the Times’ declaration to the contrary notwithstanding, has befallen this New York-based company.

Reuters, in a dispatch published in yesterday’s Los Angeles Times, reported, “Some observers attributed the weakness in Blackstone shares this week to concerns about a bill in Congress that would raise the tax rate on the earnings of publicly traded private equity firms to 35% from 15%.” Breakingviews.com, an online financial commentary that is carried in the Wall Street Journal’s Money & Investing section, reported yesterday that the tax bill “could lop billions off Blackstone’s value.” If the New York Times were a regulated stock broker giving out the kind of advice it gave out, it would no doubt write an editorial attacking itself for misleading the public.