$Palantir Technologies Inc.(PLTR)$ depends on your strategy. For trading can sell, just be prepared that price may or may not go lower to your targetted price. For investment just hold.
Buy great companies that has competitve advantages when they are at great value in a downturn. Look at their balance sheet, debt level, cashflow, growth rate, find out the intrinsic value through DCF, diversified your portfolio, size into your positions and do not go all in. In a market correction, risk manage if there is a need by rebalancing your portfolio, either take some profit and hold cash, re-enter into the position when there is a rebound, or invest into other great companies at a value. Key thing to note is that not all companies are suitable for dollar cost averaging as they may never recover. God bless.