– An iconic American company. A mysterious private investment firm. An outlandish takeover offer.

All that — and more — converged in a purported buyout offer for Avon Products Inc. on Thursday morning that sent the company's share price on a white-knuckled ride before it was discovered to be a hoax.

The episode, in cool hindsight, seems preposterous. The offer, made in a filing with the Securities and Exchange Commission, contained typos, extra spaces — even two different names of the supposed private equity firm bidding for Avon, the beauty products company that put "Ding Dong, Avon Calling" into the American vernacular.

But the brief flutter in the stock market quickly gave way to a more sobering question: how could this happen? The events focused attention on SEC filing procedures, and the SEC enforcement division is reviewing the legitimacy of the offer.

The filing came at 10:35 a.m. Twin Cities time from something called PTG Capital Partners Ltd. PTG said it was offering to buy the iconic but troubled Avon for $18.75 a share.

It was a remarkable offer — three times what Avon was trading the day before and, at about $8.2 billion, the largest leverage buyout of the year.

If it seemed too good to be true, investors didn't seem to care. The possibility of Avon being acquired had long been discussed. The stock shot up about 20 percent, and traders — humans and otherwise — churned about $91 million worth of Avon stock in 25 minutes.

Yet questions arose quickly on Wall Street and social media sites about the bid's veracity. No one had ever heard of PTG, it had never made a buyout bid before. Google searches were fruitless and, shades of Nigerian scam letters, the purported firm's own release botched its name — PTG was written as TPG twice.

It grew even more curious as calls to the primary contact on the filing, general counsel Steve Kohe, went straight to voice mail. A call to the legal adviser listed on the filing, one Michael Trose of Trose & Cox, was answered by a woman who said there was no record of him or the firm.

About 90 minutes after the filing broke, the SEC was said to be reviewing the legitimacy of the offer, and Avon said in an e-mailed statement that it never received a takeover bid from PTG and couldn't confirm that such an entity exists.

"Someone walked away with a big pot of money," said Skip Aylesworth, a portfolio manager at Hennessy Funds in Boston. "I wouldn't be surprised if part of the volume is people saying 'thank you very much, Avon,' and moving on."