Protagenic Therapeutics, Inc. (PTIX)

Protagenic Therapeutics, Inc. was a New York-based clinical-stage biopharmaceutical company developing treatments for stress-related neuropsychiatric disorders. Its stated focus was on conditions such as anxiety and depression, which are tied to hyperactive stress responses in the brain.

The company's lead candidate was PT00114, a synthetic version of teneurin C-terminal associated peptide (TCAP), a naturally occurring brain signaling peptide. Research behind the program came from academic work on TCAP's role in modulating stress, and Protagenic pursued preclinical and early clinical development with the compound. The company worked with academic collaborators and contract research organizations.

Protagenic's corporate history includes a reverse merger in 2016 with the company then known as Atrinsic, Inc., after which it operated as a publicly traded biotechnology business. Its common stock and warrants were later listed on Nasdaq, with the common stock under the symbol PTIX and the warrants under PTIXW.

As a clinical-stage company with no approved products, Protagenic relied on sales of equity and other financing to pay for research and operations. Its accumulated losses reduced stockholders' equity, which became the central issue for its Nasdaq listing.

On November 20, 2025, Nasdaq staff notified the company that it no longer qualified for listing under Listing Rule 5550(b)(1), which sets a minimum stockholders' equity requirement for the Nasdaq Capital Market. Protagenic appealed to the Listing Qualifications Hearings Panel on November 28, 2025, but withdrew the appeal on December 31, 2025, and the hearing was canceled.

The securities were suspended on January 5, 2026, which made January 2, 2026 the last day of regular Nasdaq trading, and the delisting determination became final. Nasdaq published the determination on January 13, 2026, and the securities were removed from listing at the opening of trading on February 2, 2026.

Because the delisting resulted from a failure to meet an exchange listing standard rather than a sale of the company, shareholders did not receive any acquisition consideration. The withdrawal of the appeal meant the company did not seek further time from the hearings panel to regain compliance. Following the suspension, trading in the common stock and warrants was no longer available on Nasdaq, and holders faced the typical effects of exchange delisting, including lower liquidity and less coverage by brokers and analysts. Investors who followed the stock should note that an exchange delisting does not by itself end a company's operations, and its scientific programs around PT00114 were a separate matter from its listing status. Additional information can be found in the company's SEC filings and announcements.