A gap occurs when the opening price differs significantly from the previous close and intermediate levels were not traded. The reason is usually external events between sessions: publication of reports, dividend decisions, news about the issuer, or changes in external markets.
A special case is a dividend gap: after the record date, the stock price naturally declines by approximately the dividend amount, since the dividend right no longer transfers to the new buyer. This is not a market decline but a technical adjustment, and treating it as a loss is incorrect.
On low-liquidity securities, gaps arise without any news—simply because there were no trades for several days and the next one occurred at a noticeably different price. Therefore, in the Uzbek market, a chart gap itself is not informative: first check if there was trading volume, and only then look for reasons in issuer events.