I just got paid some dividends from an ETF that I own. It is only $4, which is sitting as cash in my brokerage account. I'm aware that this is a very tiny amount of money in the grand scheme of things, so this question is more for my curiosity's sake.

The ETF doesn't offer a DRIP option, but even if it did, it probably wouldn't meet the minimum amount needed for a commission-free purchase.

What's the best thing to do with this cash? Sit on it till I have more that I can use for trading down the road?