The most basic measure of liquidity in any asset is the bid-ask spread. When the spread is small it indicates there is sufficient liquidity, however if the spread is wider the liquidity of the asset may not be sufficient, especially if an investor needs to unload a large amount of the asset. Market liquidity used to be measured by the trading volume of an asset, but that is now considered to be a flawed indicator since high trading volume does not necessarily imply high liquidity. The market global financial crisis of 2008 and the flash crash of May 2010 are the clearest examples of this.