We assume that within this limit we could trade without moving the stock price. (valueandopportunity.com)
Their individual sales are seldom if ever enough to noticeably move a stock price. (money.stackexchange.com)
«Since a multitude of variables move stock prices around, particularly in the short run, it is virtually impossible to distinguish skill from luck without a large sample size, i.e., a long record.» (mastersinvest.com)