I tend to agree with the last poster. My DH and I put $2500 in our personal account every two weeks. Our 401k is also invested every two weeks. If we have a windfall of more than $20k or so, I like to break it up into smaller amounts. 4x $5k would work in that scenario. If we are talking about $100K or more, I would break it up over a year just to avoid any dips in the market.