Ostin Technology Group Co. (OST) issued a statement addressing a plunge in its share price, which fell to $0.55 on Thursday from $9.02 the previous day. The company said it is unaware of any undisclosed material developments that would explain the volatility.

"We caution investors to rely solely on official SEC filings and statements from the company or its authorized representatives," Ostin said.

The stock fell 41% in Friday trading with intraday volume topping 115.5 million shares versus the daily average of 6.07 million.

Achieve Life Sciences (ACHV) stock dropped 36%, a day after the company priced a $45 million public offering of shares and warrants.

Volume topped 7.67 million versus the daily average of almost 265,000.

Ontrak (OTRK) priced a $4 million offering of 6.67 million shares and 26.7 million warrants at a combined price of $0.60 per share and accompanying warrants.

The stock dropped 42% as volume topped 2.92 million versus the daily average of about 26,000.

Price: 0.32, Change: -0.23, Percent Change: -41.27