March 11 (Bloomberg) -- Six Flags Inc., the owner of a chain of 20 theme parks, said there is substantial doubt about its ability to continue as a “going concern” unless a successful restructuring occurs.

The New York-based company has $287.5 million of Preferred Income Equity Redeemable Shares, or PIERS, plus accrued and unpaid dividends, due Aug. 15, it said today in a regulatory filing.

“Given the current negative conditions in the economy generally and the credit markets in particular, there is substantial uncertainty that we will be able to effect a refinancing of our debt on or prior to maturity or the PIERS prior to their mandatory redemption date,” Six Flags said in the filing.

The company may have to seek a pre-packaged or pre-arranged Chapter 11 filing if it can’t negotiate a restructuring agreement with the PIERS holders out of court, it said. That would likely happen “well in advance of” the PIERS maturity date, Six Flags added.

KPMG LLP, the auditors, said there is “substantial doubt” about the company’s ability to continue as a “going concern,” Six Flags said in the filing.

Six Flags fell 3 cents, or 14 percent, to 18 cents at 4:35 p.m. in trading after the New York Stock Exchange closed. The shares have lost 32 percent this year through 4 p.m. today.

To contact the reporter on this story: Meg Tirrell in New York at mtirrell@bloomberg.net.

Last Updated: March 11, 2009 17:25 EDT