WINDERMERE, Fla. ( Stockpickr) -- For the week ended Jan. 14, insiders at S&P 500 companies sold $163 million worth of stock in 54 separate transactions, according to a weekly report out of Bloomberg.. Amazingly, insiders bought a total of $0 worth of stock.I find it remarkable that insiders at the top companies in the world aren't finding enough value in their own stocks to motivate them to do any buying. But despite the lack of buying among the people who know the most about their company's prospects, the overall market just continues to power higher. The Dow Jones Industrial Average hit 12,000 today for the first time since June 2008, and the S&P 500 is just under 1,300. The Nasdaq is only around 300 points away from its coveted 3,000 level. These levels are key psychological price points that, when reached, mark a victory for the stock market bulls. Thus, an argument can be easily made that corporate insiders are simply selling stock into strength and taking advantage of a healthy market. Related: 4 Recent IPO Stocks to Consider But the lack of any buying is quickly becoming a major red flag. If insiders truly thought the market was a value at current levels, then they would probably be doing at least some amount of buying. The lack of any buying tells me that it's possible corporate insiders are at least a bit concerned about the future of the economy. Here's a look at the 20 S&P 500 stocks with the largest amount of insider selling. The two companies that saw the most selling for this report were Internet darling Google ( GOOG) and computer and software powerhouse Hewlett-Packard ( HPQ). Insiders at Google sold 85,334 shares, or a whopping $51.3 million worth of stock, at an average price of $615.49 a share. Insiders at Hewlett-Packard let go of 452,812 shares, or $20.6 million worth of stock, at an average price of $45.41 a share. Despite the large selling in these names, the technical picture for both stocks still looks bullish, though some hiccups are starting to hit Google after CEO Eric Schmidt recently announced he will be stepping down and handing the job over to co-founder Larry Page. Schmidt was awarded a $100 million equity award as part of his going-away package, which is a stock-and-options award with a four-year vesting period, and he's expected to continue on at the company as executive chairman of Google's board. The entire insider selling at Google for this report was done by Page, who exercised options to lock in profits he had on the stock.