Whats going on with ISRGs options Nov 17 puts interest stocks

http://m.nasdaq.com/article/are-options-traders-betting-on-a-big-move-in-intuitive-surgical-isrg-stock-cm878482https://charts.stocktwits.com/production/original_101799723.png?1510872344Ive been trading for less than a year now so Im not the best at reading into these types of news. My understanding is that theres an absurdly large amount of interest in mid-$200 strike price puts that expire tomorrow (Nov 17). Why would anyone pick up puts that are about to expire in less than a day if theyre not 100% sure about some type of crazy selloff tomorrow? Could this be insiders knowing that some big news is gonna be coming out tomorrow?

http://m.nasdaq.com/article/are-options-traders-betting-on-a-big-move-in-intuitive-surgical-isrg-stock-cm878482 https://charts.stocktwits.com/production/original_101799723.png?1510872344 Ive been trading for less than a year now so Im not the best at reading into these types of news. My understanding is that theres an absurdly large amount of interest in mid-$200 strike price puts that expire tomorrow (Nov 17). Why would anyone pick up puts that are about to expire in less than a day if theyre not 100% sure about some type of crazy selloff tomorrow? Could this be insiders knowing that some big news is gonna be coming out tomorrow?