By Fred Fuld

SAN FRANCISCO (

TheStreet

) -- The bulls aren't the only ones responsible for big up moves in the market. Sometimes the bears pitch in to do their part, too. According to Jim Cramer, short-sellers were at least partly to blame for a recent huge move in the market, particularly in the energy and materials sectors.

"We've got a real squeeze going here, a gigantic one,"

he wrote in a July 15 post to his

RealMoney

blog. "In other words, it isn't just buying -- it's short-covering."

A short squeeze takes place when short-sellers quickly buy in shares of the stock, often on unexpected good news, in order to close out their positions, driving the price of the stock up sharply. Stockpickr has several resources for researching short squeezes, including its

Answers

forum, where Stockpickr members can ask and answer questions and where experts such as

Scott Rothbort

check in regularly to offer their insight. The

Professional Portfolios

are another useful tool, listing the shareholdings of mutual funds, hedge funds and money managers and giving investors the opportunity to see what stocks are owned by the pros.

With Cramer's analysis in mind, Stockpickr has reviewed the short interest in the materials and oil stocks and compiled a list of

potential short squeezes

.

To read more,

visit Stockpickr.com

.

-- Written by Fred Fuld in San Francisco.

Stockpickr is a wholly owned subsidiary of TheStreet.com.