<prompt> Human: Im in the accumulation phase, and I have no cash as all my retirement contributions are being put towards investments stockbond funds. I was thinking it might be a good idea to keep some cash in my accounts for buying during a downturn. What do you think is a good amount or percentage of capital to keep in cash for buying equities on sale? Is there a reason why I should NOT pursue this strategy?EDIT: Thanks for the replies so far, I appreciate the comments! Since many are saying similar things I will post further information here. My current strategy does NOT involve market timing. Rather, I make regular contributions to stockbond funds and I follow asset allocation principles.  <response>: Whatever money you keep in cash will be missing out on earnings while waiting for the next big crash. While buy low, sell high is an admirable goal, Ive found that time in the market, not timing the market to be the easier advice to follow. 