Quotes and execution · 5 min read
Bid, ask, and spread: why can a new position show a loss?
Understand bid, ask, last price, and the bid-ask spread. See why a new position can show a loss, and how spread differs from slippage and trading fees.
A position can show an immediate unrealized loss without a clear decline in the displayed quote. The quote, last trade, and position mark may use different prices. Understanding bid and ask helps identify which difference you are seeing.
Bid, ask, and last are different observations
Bid is a buyer’s quote; ask, or offer, is a seller’s quote. A screen usually shows the best quotes within its data coverage. Market coverage and delay depend on the feed and permissions. Last is a recently reported execution, not a quote that necessarily remains available.
Investor.gov’s order guide notes that the last trade need not be a market order’s execution price. An immediately executable buy generally encounters offers, and a sell encounters bids; price improvement, available size, and changing quotes affect actual results.
An eight-cent spread example
Assume stable quotes and sufficient size: bid $10.00, ask $10.08. Spread = ask − bid = $0.08. This fictional example illustrates arithmetic, not an order recommendation:
| Assumption | Result |
|---|---|
| Buy 100 shares at $10.08 | $1,008 cost before fees |
| Platform marks the position at the $10.00 bid | $1,000 displayed value |
| Difference | −$8 |
The quotes need not have moved for that negative mark to appear. Other platforms may mark positions using last, midpoint, or another convention. Check actual fills, valuation rules, and fees before attributing a displayed loss to the spread.
Spread is not slippage
Spread is the distance between two quotes at one moment. Slippage is the execution’s difference from a specified expectation or benchmark. A slippage claim is incomplete without the reference price and time. Quote changes, insufficient depth, and delayed data can matter.
If half an order fills at $10.08 and half at $10.12, its average is $10.10. The two-cent difference from a $10.08 reference is distinct from the original eight-cent spread. FINRA explains why quotes and executions can differ.
Consider relative size and available depth
Eight cents is a different proportion of a $1 stock than of a $100 stock. Using midpoint as the denominator, this example’s relative spread is approximately 0.08 ÷ 10.04, or 0.80%. A different denominator produces a different measure; identify it.
One quote level does not describe the entire book. Displayed size can be small or change before an order arrives. High volume or a large float cannot independently guarantee execution quality. See the session guide for extended-hours context.
Keep evidence that can be checked
In the FennEdge workspace, keep the observation time, session, bid, ask, last, and source in research notes, then compare them with actual broker execution records. A research page is not an execution confirmation. If contemporaneous quotes are unavailable, keep that uncertainty explicit.
Continue with market, limit, and stop orders or look up abbreviations in the trading glossary.
This article explains common concepts; examples are not trading recommendations.
