Co-Diagnostics, Bio-Key International, and Nauticus Robotics are the 3 Penny Stocks to watch on October 28, 2025, based on TipRanks’ Penny Stock Screener tool. Penny stocks are defined as stocks that trade at or below $5 per share and have a market capitalization below $300 million.
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The Penny Stock Screener helps investors scan stocks based on numerous parameters, including Sector, Price Target Upside, Smart Score, Analyst Consensus, Dollar Volume, and Price Change.
We leveraged the tool to pick the top three penny stocks with the highest Dollar Volume as of the close on October 27, 2025. Simply put, Dollar Volume is the number of shares traded on a particular day multiplied by the day’s share price.
Co-Diagnostics (CODX) – Co-Diagnostics is a molecular diagnostics company that develops, manufactures, and markets diagnostic tests primarily based on polymerase chain reaction (PCR) technology. On October 27, CODX had a Dollar Volume of $1.40 billion, while its stock price skyrocketed by more than 259%.
The company announced the formation of a joint venture, CoMira Diagnostics, with Arabian Eagle, a regional manufacturing and distribution company based in the UAE. The JV will engage in the research, development, manufacturing, assembly, and sales of Co-Dx technologies and intellectual property, including its upcoming Co-Dx PCR point-of-care platform, in Saudi Arabia and 18 other countries in the Middle East and North Africa.
Bio-Key International (BYKI) – Bio-Key specializes in identity and access management (IAM) solutions with a focus on biometric authentication technologies. Yesterday, BYKI had a Dollar Volume of $270.99 million, accompanied by a stock price surge of 32.5%.
The company announced a partnership with Scandinavian IT distributor IT2Trust, whereby the latter will use its connections to distribute BIO-key International’s technology across Denmark, Sweden, Norway, and Finland.
Nauticus Robotics (KITT) – Nauticus Robotics develops cloud-connected subsea robots and software, providing advanced ocean robotic solutions designed to address the challenges facing the world’s marine environment. On Monday, KITT had a Dollar Volume of $176.75 million, while its stock price rose by 14%.
Nauticus Robotics announced that it has secured a $250 million equity line of credit (ELOC) to support its next growth phase. The funding gives Nauticus the flexibility to make strategic acquisitions and expand into the fast-growing market of deep-sea rare earth and mineral exploration.
To find more penny stocks like these, you can take a look at TipRanks’ Penny Stock Screener tool. It shows a list of all penny stocks, their price movement, and other vital data.