We can see that since the open of yesterday, the S&P500 has barely moved, while the stocks bought yesterday at the open are doing rather well on average. This means that we are still in a stock selection environment where we need to focus on specific stocks instead of on noise.
However, if a wave of selling panic hits, you can be sure that leading stocks will fall much harder than the S&P500.
This is not specific to today's environment: it is always like that.
By the way, I also shorted ISRG at 370, because the opening gap hardly attracted any money.
Pascal