In January, the number of corporate executives buying shares in their own firms was only 279, the lowest it has been since 1988, according to a recent article in The Wall Street Journal.

The number of sellers, on the other hand, has been above average, the article says. Investors use such information to gauge expectations from corporate insiders. “Sales,” the article says, “can show wariness about valuations, while purchases can signal confidence that more gains lie ahead.”

“The fact that we’ve gotten more selling is a sign of concern that maybe the market has gone a little too far too fast,” said Ed Clissold, chief U.S. strategist at Ned Davis. The article clarifies, however, that absolute numbers alone don’t “portend an imminent decline in stocks. Corporate executives can sell their stockholdings for many reasons, and selling generally outpaces buying regardless of market conditions.”

The article quotes John Buckingham, chief investment officer at Al Frank Asset Management, who argues that, while people sell for a variety of reasons, “generally there’s only one reason to buy—you think your company is undervalued.”