Locked Market

A short-term situation occurring within a market where both the bid and ask are identical, resulting in no bid-ask spread.

Investopedia Says:
This usually occurs in stocks that are highly volatile and experience a significant trading volume. Locked markets are typically corrected immediately through subsequent trades. This abnormal market condition occurs mainly on the Nasdaq exchange for orders entered before the opening bell.

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Said of a market where the bid price equals the asked price. This occurs in very competitive markets, and for only brief periods. The market will unlock, and bid-asked quotes will diverge, after the trades are made.