NEW YORK (CNN/Money) - Tyco International has drawn one step closer to completing a much needed initial public offering of its financial services unit, CIT.

On Wednesday, CIT Group Inc filed an amendment to the registration statement for its pending IPO. The development helped send shares of Tyco, down 80 percent this year, soaring in after-hours trading and up more than 20 percent in regular trading Thursday morning.

In that filing, CIT restated second quarter financial statements to reflect a $4.5 billion write down in goodwill related to Tyco's acquisition of CIT last year. The Securities and Exchange Commission and Tyco had been in discussions regarding accounting issues at CIT and there was speculation that these talks could delay the offering, tentatively scheduled for the end of this month.

Tyco did not provide a date for the IPO. But the offering could raise a maximum of $5.8 billion, a sizeable drop from its initial filing. In April, New York-based CIT filed its initial registration statement, an S-1, hoping to raise as much as $7.15 billion.

Tyco, heavily in debt, needs the money the CIT IPO would raise, and some investors had been speculating that Tyco would have trouble unloading the unit, either through the IPO or through a sale. The company has said it hopes that a sale, combined with cash it is currently generating, would help it to pay down $10 billion in debt. As of March 31, the company had $20.5 billion in debt due within a year.

That has been one of the many factors weighing on shares in recent weeks. But news of the amendment Wednesday night calmed those fears, and triggered the jump in after-hours trading.

"It's well within the realm of advancing in a timely fashion," analyst Ben Holmes, of Morningnotes.com, said of the CIT offering. "For similar deals of this size it's very much on track."

Despite the positive news about the IPO, Moody's downgraded Tyco's debt for the second time in a week. In a statement the rating agency said, "Even with the anticipated debt reduction from the CIT transaction, the potential risks attendant to the widening array of management and corporate governance issues at Tyco render the company's credit profile inconsistent with an investment grade rating."

CIT plans to sell 200 million shares at $25 to $29 each via co-lead underwriters Goldman Sachs and Lehman Brothers. J.P. Morgan, along with other investment banks, are included in the syndicate. The offering will trade on the New York Stock Exchange under the symbol CIT.

CIT will likely file more amendments if the SEC has any more questions or requires more disclosure, Holmes said. "The SEC doesn't approve or disapprove of any IPO," he said. "All they are requiring is a fair and full disclosure."

Separately, Tyco said that the Securities and Exchange Commission will open a formal investigation into Dennis Kozlowski, who resigned as CEO last week before being indicted for sales tax evasion. The SEC investigation into Tyco and its ex-CEO has been rumored for days.

"The company is not aware of any other pending investigation into its accounting practices other than on these issues," Tyco said late Wednesday.