What Is Bid Size in Investing?

Bid Size in Investing Explained in Less Than 4 Minutes

Definition
Bid size in investing is the number of shares an investor or market maker is willing to buy at the current best bid price, or the highest price a buyer will pay to buy a specific number of shares.
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Bid size in investing is the number of shares an investor or market maker is willing to buy at the current best bid price, or the highest price a buyer will pay to buy a specific number of shares.

Bid size in investing is often an important number for traders selling a significant amount of shares. Here’s a more in-depth look at what bid size is, how it works, and where you can find it.

Definition and Examples of Bid Size in Investing

Bid size in investing is the amount of shares an investor is willing to buy at the best current bid price. Bid sizes are presented in lots, which are typically 100 shares.

Note

The bid size is typically a limit buy order from another investor or market maker. For stocks with larger prices, the lot may be only 10 shares. Thinly traded stocks that have a low price but no bids or asks at 100 shares trade in “odd lots.”

The bid size will often be shown next to the bid price. Let’s say you have 2,400 shares of Target stock to sell. You check the current bid price and size on an exchange platform or some financial sites. Say, for example, you saw the current bid price was $221.60 and the bid size was 900. (Some websites/brokerages will show this information as $221.60 (9)).

So, in this hypothetical scenario, If you enter a sale order for 2,400 shares, you know that 900 of them could be purchased for $221.60 per share. To figure out the price you could sell the rest of your shares, you’ll need to get a Level II quote on bid price and bid size.

How Bid Size in Investing Works

Bid size in Level I quotes shows the size for the best current bid prices, other current bid sizes can be found using Level II market data.

Note

Level II market data isn’t available on financial sites such as Yahoo Finance, and is often not even available for basic-level traders on brokerage sites. For example, Robinhood only makes Level II for Nasdaq stocks available for Robinhood Gold members, and TD Ameritrade only makes it available on its “thinkorswim” trading software.

These programs show an entire market depth picture for a stock, including sizes of bids and asks, and their prices. Here is a hypothetical example of Level II information you may find:

Size Bid Ask Size
900 $221.60 $221.65 500
1,000 $221.50 $221.58 400
1,100 $221.40 $221.48 400
1,300 $221.30 $221.38 300
1,300 $221.20 $221.28 200

In this case, if you sell 2,400 shares, you’d sell 900 at $221.60 per share, 1,000 at $221.50, and the final 500 at $221.40.

This is a microcosm of how the market works. There is more selling pressure (2,400 shares) than buying pressure (900), so the stock price would fall. Of course, this happens hundreds or thousands of times per day, and much of it is a result of professional market makers or high-speed trading funds.

Note

Market makers are professionals who specialize in certain areas of the market, or even just one specific stock, and work to increase liquidity in that area by buying and selling shares at the current market price.

In the above example, it is likely a market maker that puts in the limit order book that becomes the market depth picture above. The market maker buys your shares immediately, then sells them later on at the ask price, earning money on the spread. Without the market maker, there may not be another trader willing to buy at your price.

Bid Size vs. Ask Size

Ask size is the opposite of bid size. It is the amount of shares someone is willing to sell at the best possible ask price. Traders can use ask size in a similar way to bid size. Traders looking to buy a stock can use ask size to see what the price and number of shares available are.

In investing, bid price is the price a buyer is willing to pay and ask price is the price a seller is willing to take. The difference between the two is called the spread.

Key Takeaways

  • Bid size is the number of shares someone will buy at a particular bid price, or the price is the price a buyer is willing to pay.
  • Bid sizes are typically expressed in “lots,” which are usually 100 shares each or 10 shares each for large stock prices.
  • Traders can use bid sizes to determine how many of their shares could be sold at a particular price.
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Sources
The Balance uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Fidelity. “Bid Size.” Accessed Feb. 9, 2022.

  2. Robinhood. “What's Level II Market Data?” Accessed Feb. 9, 2022.

  3. Thinkorswim. “Level II.” Accessed Feb. 9, 2022.

  4. U.S. Securities and Exchange Commission. “Market Makers.” Accessed Feb. 9, 2022.

  5. U.S. Securities and Exchange Commission. “Bid Price.” Accessed Feb. 9, 2022.

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