Lost 250000.0 in 2009 when business investment went bankrupt. How long can I write off short and long term gains in stock market against this business loss??

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With respect to capital loss carryovers, there is no limit in terms of years; you can carry them over to subsequent tax years until they are entirely used (offset).

See https://www.irs.gov/newsroom/capital-gains-and-losses-10-helpful-facts-to-know-0