Market Cap

Mega cap (>$200B): AAPL, MSFT. Large cap ($10-200B): big blue chips. Small cap ($300M-$2B): volatile, higher beta. Micro cap (<$300M): penny-stock territory. Market cap buckets define how stocks behave and what kind of volume they attract. ### What it is, and what it is not Share price times outstanding shares. It is a sticker value, not money. Nobody paid it, nobody can extract it, and it is not what the company would sell for. It is the last trade, which may have been a few hundred shares, multiplied across every share in existence. Useful as a label. Dangerous as a belief. ### The number the funds actually use Index providers do not weight by headline market cap. They weight by **float-adjusted** market cap. FTSE Russell adjusts the shares in its equity indices to include only those available to the public. So two companies with an identical market cap can carry very different index weight and very different real tradeable supply, depending on how much sits locked with insiders, governments, treasury, private equity or a single strategic holder. Market cap tells you the size of the company. Float-adjusted market cap tells you the size of the *market* in it. That is exactly why market cap and float sit next to each other in this glossary, and why reading one without the other misleads you. ### The bucket changes the rules, not just the vibe Size has hard, written consequences: - **Disclosure.** SEC filer status runs off public float. Under Rule 12b-2, a public float of $75 million or more but under $700 million generally makes an issuer an accelerated filer, and $700 million or more generally makes it a large accelerated filer, with heavier reporting obligations. Bigger names are simply better documented, which is part of why they behave more predictably. - **Volatility guardrails.** Under Limit Up-Limit Down, Tier 1 (the S&P 500, the Russell 1000, certain ETPs) gets a 5% price band for stocks priced above $3.00. Tier 2, which is everything else, gets 10% at that price level, and wider bands further down the price scale. Per FINRA, a stock that stays in its limit state 15 seconds is paused for five minutes. The big names are held to a tighter leash by design. Smaller ones have far more room to run before anything intervenes. - **The bottom of the range.** The SEC's microcap bulletin warns that these stocks are historically less liquid, more thinly traded and more volatile than the stocks of larger companies, and that this makes them easier to manipulate. ### The common mistake Treating market cap as a safety rating. It is not. Large caps fall, sometimes very far. What cap reliably forecasts is not direction, it is **behaviour**: how deep the book is, how tight the spread is, how much your order moves the tape, how much slippage you should budget for. Read it as a mechanics forecast, not a risk score.