Venture investment during recessions may actually be more productive, per dollar spent, than during booms, when money is showered on many variants of the same business plan.

Or, another way of saying the same thing, the Fed will reduce reserves at healthy banks--thereby worsening their liquidity--dollar for dollar with the loans they are making to the investment banks.

It is calculated as a ratio of the money gained or lost on that investment relative to the amount of money invested, and is typically stated as a percentage rather than as a dollar value.