Largest Micro-Cap Companies by Market Capitalization

Micro-cap stocks are publicly traded companies with a market capitalization roughly between $50 million and $300 million — sitting above nano-cap stocks (below $50 million) and below small-cap companies ($250 million to $2 billion). The exact thresholds vary between data providers, but the U.S. SEC generally defines micro-cap stocks as companies with a market capitalization under $250–$300 million.

More established micro-cap companies trade on exchanges like the NASDAQ Capital Market or the American Stock Exchange (AMEX), while many others are quoted on OTC platforms such as the OTCBB, OTC Link, or the Pink Sheets. Compared to larger stocks, micro-caps typically receive far less analyst coverage and have limited publicly available financial information, which can lead to pricing inefficiencies.

The sectors most heavily represented in the micro-cap universe include:

• Healthcare and biotechnology: The majority of biotech stocks fall into the micro-cap category, often representing companies in early development stages.
• Financial services: One of the top sector weightings across micro-cap indices.
• Technology: Smaller tech firms focused on specialized products or services.
• Consumer discretionary and producer durables: Companies serving niche consumer and industrial markets.

The Russell Microcap Index, launched on June 1, 2005, and maintained by FTSE Russell (a subsidiary of the London Stock Exchange Group), is the primary benchmark for this segment. It includes approximately 2,000 of the smallest U.S. equities. The iShares Micro-Cap ETF (IWC) tracks this index. S&P Dow Jones Indices also maintains the Dow Jones U.S. Micro-Cap Total Stock Market Index, which is rebalanced quarterly.

Federal authorities have noted that micro-cap stocks have historically been targeted by fraud and manipulation schemes due to limited public information — a factor worth keeping in mind. Almost every large-cap company today began its journey as a small company.

The table below ranks the largest micro-cap listed companies by market capitalization, updated with live data.

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