Are there any mutual funds comprised of ETFs that do strategic rebalancing? Not rebalancing on a timed schedule but doing it on a basis that is relative to the situation at the time of the rebalance.

I know a person could spend the time doing it on their own but I don't have the time. I would like to contribute to a fund that does this automatically when it is deemed beneficial.

Maybe a fund comprised volatile growth ETFs. Sell part of the ups and buy the downs to increase share volume but always remain 100% in the market.

Can you name some funds that do this?