There was once a rule of thumb that insider selling over 20x in any given period is bearish. We would be overly generous and say bearish is 30x, no 50x, oh why not: 100x more sellers than buyers. So what does a ratio of 351.3x sellers to buyers indicate? Because this according to Bloomberg is last week's insider activity in S&P500 names in the past week. Indeed, in the past week insiders purchased a total of $2.75 million notional in corporate stock, across 13 different companies, with the bulk focusing on Mead Johnson and Comcast. This was offset by a whopping $1 billion + in insider sales, as corporate officers couldn't wait to dump MetroPCS ($151 million), Sara Lee ($133 million), and, surprise, Microsoft ($127 million). Compare this to last week's insider purchases of just over $1 million and sales of $650 million and make your own conclusions.