When someone says Apple is a "mega-cap" company or calls a biotech startup a "small cap," they are talking about market capitalization — the total value of all a company's outstanding shares.
The Formula
Market Cap = Stock Price x Shares Outstanding
If a company has 1 billion shares outstanding and each trades at $150, its market cap is $150 billion. That is the price tag the market puts on the entire company.
The Size Tiers
While there are no official boundaries, investors generally use these ranges:
Mega Cap — above $200 billion The biggest companies in the world. Think Apple, Microsoft, Amazon, Nvidia. These are household names with global operations, massive revenues, and dominant market positions. They tend to be the most stable but also the hardest to grow quickly (it is difficult to double a $3 trillion company).
Large Cap — $10 billion to $200 billion Well-established companies with proven business models. Most of the S&P 500 falls in this range. They offer a blend of stability and growth potential. Examples include companies like Starbucks, FedEx, and General Motors.
Mid Cap — $2 billion to $10 billion Companies that have proven their business model but still have significant room to grow. Mid-caps often fly under the radar of big institutional investors, which can create opportunities. They carry more risk than large caps but also more upside.
Small Cap — $300 million to $2 billion Younger or niche companies. Higher growth potential comes with higher volatility and risk. Less analyst coverage means less information is publicly available, which can be both an opportunity and a risk.
Micro Cap — below $300 million Very small companies, often with limited trading volume. These carry the highest risk — many micro-caps never become profitable. Most casual investors are better off avoiding this tier.
Why Size Matters
Market cap affects almost everything about how a stock behaves:
Volatility: Smaller companies tend to have larger daily price swings. A mid-cap stock might move 3-5% on an ordinary day, while a mega-cap rarely moves more than 1-2%.
Liquidity: Larger companies have more shares trading every day, making it easy to buy and sell at fair prices. Smaller stocks can have wide bid-ask spreads.
Analyst Coverage: Mega-caps might have 30+ Wall Street analysts following them. A small-cap might have two or three. Less coverage means less efficient pricing — but also less information for you to work with.
Growth Potential: A $5 billion company doubling in value is far more plausible than a $500 billion company doing the same. If you are looking for high growth, you generally need to look at smaller companies.
Dividend Behavior: Larger, more established companies are more likely to pay dividends. Many small and mid-cap growth companies reinvest all profits rather than paying cash to shareholders.
What Stock Feeder Covers
Stock Feeder's universe includes roughly 550 stocks from the S&P 500 and NASDAQ-100 indices. This means the coverage skews heavily toward large and mega-cap companies, with some mid-caps included through the NASDAQ-100.
The screener lets you filter by market cap, so you can focus on the size tier that matches your strategy:
- •Set minimum market cap to $100B to see only mega-caps
- •Set the range to $10B-$50B to focus on mid-to-large companies
- •Use the $2B minimum to include the smallest names in the universe
How Cap Size Fits Into a Portfolio
Many financial advisors suggest building a portfolio across multiple cap sizes:
Core holdings (60-70%): Large and mega-cap stocks for stability and dividends. These are the foundation — companies you plan to hold for years.
Growth allocation (20-30%): Mid-cap stocks with strong earnings momentum. These provide the portfolio's growth engine.
Opportunistic positions (5-10%): Smaller names with high conviction. Higher risk, but a single winner can meaningfully boost returns.
The key principle is diversification — spreading across sizes so you are not entirely dependent on any single tier performing well.
The Bottom Line
Market cap is the simplest measure of "how big is this company?" and it should inform your expectations:
- •Mega-caps: safety, dividends, slow growth
- •Large-caps: balance of stability and growth
- •Mid-caps: growth potential with moderate risk
- •Small-caps: high growth, high risk
When you see a stock's market cap on Stock Feeder, it instantly tells you what league the company plays in — and what kind of risk-reward profile to expect.