Forever 21 has declared bankruptcy for a second time and expects to close over 350 stores in the United States and Puerto Rico by May 1, unless the business is purchased by a new buyer, court filings show.

F21 OpCo, LLC, the company and licensee of the brand in the U.S., filed a Chapter 11 case in the U.S. Bankruptcy Court for the District of Delaware this week.

"The company may pivot away from a full wind down of operations to facilitate a going concern transaction. If there is an actionable going concern proposal that warrants stopping ongoing store closing sales, the company will exercise its business judgment and determine the appropriate course of action," a spokesperson for the fast-fashion retailer told ABC News.

Brad Sell, the chief financial officer of F21 OpCo, LLC, cited international competitors and growing costs among the reasons behind Forever 21's downturn in a press release Sunday.

"While we have evaluated all options to best position the Company for the future, we have been unable to find a sustainable path forward, given competition from foreign fast fashion companies, which have been able to take advantage of the de minimis exemption to undercut our brand on pricing and margin, as well as rising costs, economic challenges impacting our core customers, and evolving consumer trends," Sell said in part. "As we move through the process, we will work diligently to minimize the impact on our employees, customers, vendors and other stakeholders."

Sell's mention of a de minimis exemption refers to a congressional law that allows for imported products under $800 to enter the U.S. without any duties, tariffs or taxes, according to the International Trade Administration, an agency within the U.S. Department of Commerce.

In court filings, Forever 21 further cited direct competitors Shein and Temu, who it said take advantage of de minimis exemptions.

"Certain non-U.S. online retailers that compete with the Debtors, such as Temu and Shein, have taken advantage of this exemption and, therefore, have been able to pass significant savings onto consumers. Consequently, retailers that must pay duties and tariffs to purchase product for their stores and warehouses in the United States, such as [Forever 21], have been undercut," the company wrote in part in its filing.

Once a staple at American malls, Forever 21, which was founded in 1984, was at its peak a customer favorite and a market disruptor for its low-cost and trendy clothing options. The company filed for bankruptcy back in 2019 and found a buyer when Authentic Brands Group teamed up with Simon Property Group and Brookfield Property Partners to purchase the brand in 2020.

The new development comes despite a resurgence in nostalgic retail shopping and amid speculation in late February that the retailer would declare bankruptcy for a second time and close hundreds of U.S. stores.

"[Forever 21] continues to explore strategic options, including a potential sale … the efforts are ongoing and no final decisions have been made," a Forever 21 spokesperson told ABC News at the time.

ABC News has reached out to Shein and Temu for comment.

Forever 21 has over 540 store locations globally. Its international stores are unaffected by the bankruptcy filing as they remain operated by other licensees.

Editor's note: This article has been updated to include the most recent information from Forever 21's bankruptcy court proceedings.