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What is an odd lot in stocks?

In one line: An odd lot is a stock order or holding smaller than a round lot, which for most US stocks means fewer than 100 shares.

Trading glossary · Updated 2026-10-21

The short version

Stocks have a standard trading block called a Round lot. For most US stocks, that's 100 shares. Anything smaller is an odd lot. So 1 share, 37 shares or 99 shares are all odd lots.

Fractional shares, like 0.4 of a share, are smaller again. Many brokers offer them too.

Why your trades are often odd lots

Good sizing almost never lands on a round number. Here's a math example.

• Your account is $5,000. You risk 1% a trade, so $50.
• You buy at $42.00. The chart says your Stop loss belongs at $40.65. That's $1.35 of risk per share.
• $50 ÷ $1.35 = 37.0. So you buy 37 shares.

That's an odd lot, and it's exactly right. The size came from your risk, not from a habit of buying 100. The position size calculator does this math for any trade.

A math example, not a promise. The trade can still lose, and gaps can carry price past a stop.

Do odd lots fill normally?

At most brokers today, yes. You place the order and it fills like any other.

One quirk: small orders waiting on the book may not show up in the quoted best bid and ask the way 100-share orders do. So now and then you may see a fill slightly better than the quote you saw. That's normal.

Why it matters

Odd lots free you from a bad rule: "I need to buy 100 shares." That rule makes risk bounce around from trade to trade. With odd lots, every trade can risk the same small slice. More in how much to risk per trade.

A common mistake

Rounding up to 100 shares "because it looks cleaner." In the example, 100 shares would risk $135, not $50. That's 2.7% of the account on one idea. Round down, not up, when the math gives you a messy number.

Questions