Huh? Its percentage has nothing to do with it. The DOW is price weighted. If NVDA doubles (+136), that will be good for about 950 DOW points. If UNH ($535) goes up 136 points, the DOW gains the same 950 points.
Of course it does. If UNH doubles it will add 10% to the DOW while NVIDIA will only add 2.5% if it doubles. And a 50% crash in UNH will take the Dow down 5% vs 1.25%. The effect is more pronounced on the down side. Because NVIDA can't fall more than 136 points from current levels, while UNH can fall much more than that.