It’s widely recognized that the transaction costs incurred by investors are made up of two primary components: brokerage fees (i.e., commissions), and the bid-ask spread. While most people are familiar with brokerage fees, fewer people are familiar with the concept of the bid-ask spread.
The bid-ask spread, sometimes referred to as the bid-offer spread, refers to the difference between the prevailing price at which you could sell a particular investment (the bid price) and the price at which you could buy it (the ask price). In other words, we’re talking about the highest price that a buyer is willing to pay for an asset, and the lowest price that a seller is willing to accept.
The difference between the bid price and the ask price is the referred to as the “spread, ” and it goes to the so-called “market maker.” Market makers are firms that provide market liquidity and help to smooth out buyer/seller imbalances (and ultimately profit) by standing ready to buy assets at the bid price and to sell them at the ask price.
The reason that he bid-ask spread matters to people like you and me is that whenever you make a trade, you’re instantaneously “in the hole” by a small amount, even before we consider brokerage fees. It’s worth noting that the bid-ask spread is typically larger on thinly-traded (i.e., relatively illiquid) investments such as micro-cap stocks as compared to more widely traded (i.e., relatively liquid) investments.