Shares of Enron Corp. fell nearly 40 percent on Thursday amid investor concern the company's once-mighty energy trading business will not see a revival any time soon.

The stock was off 27 cents, or 26.7 percent, at 74 cents, in trade on the New York Stock Exchange. Early in the day, it had fallen as low as 61 cents.

Enron filed for Chapter 11 bankruptcy protection on Sunday and obtained $1.5 billion in debtor-in-possession financing on Monday in the hopes it will be able to to reorganize and regain lost business.

The company's stock has lost more than 97 percent of its value since reporting the losses in mid-October. Shares are down from a high of more than $90 in August 2000.

Several investment banks, including Swiss bank UBS AG , Citigroup, and J.P. Morgan Chase, on Monday were in preliminary talks with Enron to form a joint venture that would own the Houston-based firm's energy trading business, sources said.

The news sparked a two-day rally in the stock, which on Wednesday closed above $1 for the first time in a week.

"Perhaps yesterday was still some carry-over from J.P. Morgan and Citicorp putting new money in in hopes that we would start to see some announcement of a joint venture with the trading," said Mike Heim, an analyst with A.G. Edwards & Sons. "Today is just disappointment that we're not hearing any announcements."

Enron's free-fall was sparked in mid-October when it posted its first quarterly loss in more than four years and investors soured on the company, valued at almost $80 billion a year ago and about $1 billion after disclosures of murky dealings.

Investors must be prepared for further volatility in the stock, Heim said.

"We're just going to have to face the fact that this is going to be an extremely volatile stock for the next couple of days," he said. "People are used to thinking that a 30 cent move in the stock is nothing for Enron, but at these prices obviously it is a significant movement."