There is a simple algorithm one can use to determine how much to put in or take out based on what the market is doing month to month. I don't remember the name

There is a simple algorithm one can use to determine how much to put in or take out based on what the market is doing month to month. I don't remember the name of it. But if the market sector is going up you increase investment by X%. Going down decrease investment by X%. I think it works mostly because it avoids going all in at the top and all out at the bottom. Which is the strategy a lot of naive investors end up doing.