Stock market pessimists are betting with less conviction of late. Short interest dipped 1% during the second half of February and has fallen 14% over the past year, according to New York Stock Exchange data reported Tuesday.

Short-selling is the act of selling borrowed shares in hopes of buying them back later at a lower price and pocketing the difference. Short interest is the outstanding number of shares sold short.

Shares of the three companies below, all S&P 500 members, are defying the broad decline in short-selling. Bets against them are heavy and rising. Each company s short interest has increased in recent weeks and now equals more than 10 days worth of that company s typical trading volume. The median for S&P 500 members is 2.4 days.

There are at least two reasons not to read this list as a recommendation for short-selling. First, shorting is best left to deep-pocketed and experienced investors, as it carries serious risks. Second, high short interest can sometimes result in the feared short squeeze, during which a stock s price shoots higher as short-sellers scramble to buy the shares they owe.

Harley Davidson

Short interest ratio: 11

Harley Davidson (HOG) has long collected premium prices for its motorcycles, which is why the stock multiplied about 190 times in value in just under two decades ended 2006. However, those high prices have made customers reluctant to buy during the recent downturn in consumer spending. Company sales fell by 22% from 2007 to 2009. Here s one reason to believe business won t return to peak levels anytime soon: BMO Capital Markets, an investment bank, recently studied the correlation between Harley s stock price and measures like the unemployment rate, interest rates, gross domestic product and consumer sentiment scores. It found that the Case-Shiller index of house prices did more than any of these to explain the stock s movements. That suggests that America s house bubble might also have been a bike bubble. To the company s credit, it has cut production and exited non-core businesses in order to more comfortably ride out the downturn.

Meredith

Short interest ratio: 13

Meredith (MDP) publishes magazines and books and owns television stations. Its flagship magazines include Better Homes and Gardens, Family Circle and Ladies Home Journal. Advertising revenues have increased lately, but future quarters are difficult to forecast, analysts say. If the nascent economic recovery fails, companies might slash advertising budgets again. Even if it doesn t, a steady shift of print readers to the Internet, which has a colossal supply of pages on which to post ads, threatens to crimp ad rates. Analysts call Meredith a well-run company with a dominant position in women s magazines, but investors should note that the stock price has tripled in a year.

Robert Half International

Short interest ratio: 10

As a staffing agency, Robert Half (RHI) matches workers, of which there are plenty available at the moment, with jobs, of which there are frustratingly few. The company s sales have fallen by about one-third over the past two years. The stock price looks high relative to forecast profits for either this year or next year, and only average compared with the robust profits the company earned during its last business peak in 2007. One plus for shareholders: management launched a dividend payment in 2005 and has boosted it each year since. The stock s current yield is 1.8%. Payments should cost about $75 million a year, which looks affordable relative to Robert Half s $125 million in free cash flow projected for this year and its more than $300 million in net cash sitting on the books.