Paper: "Mathematical Models for Stock Pinning Near Option Expiration Dates"

Another paper, "Mathematical Models for Stock Pinning Near Option Expiration Dates" [pdf] by Marco Avellaneda , Gennady Kasyan and Michael D. Lipkinz,

"We consider the phenomenon of 'pinning' of stock prices at option strikes around expiration dates. Pinning at the strike refers to the likelihood that the price of a stock coincides with the strike price of an option written on it immediately before the expiration date of the latter."

Yes, pinning does happen but more because of marketmaker hedging than conspiracy.