Question: why does having a lot of puts at $400 make it a lure? (If by lure you mean attractive stock price to approach?) Anything above those keeps them from being executed, so it seems more like it would be more of a support point than attraction point.So we do see that there are 29K Put contracts open at the $400 Strike. This will indeed be a powerful lure for options writers (mostly Market Makers), but there are also substantial numbers of Put contracts open at 500, 550, and 600 Strikes.
Is there a secondary effect involved?