Mutual fund company Fidelity Investments is setting itself on a collision course with rivals by rolling out a pricing service designed to make the roughly $800bn market for securities lending more transparent, according to people familiar with the firm's plans.

In securities lending, money managers lend out stocks and bonds, frequently to short sellers, collecting a fee for the service. The short sellers, who want to bet against the securities, sell them, hoping to buy them back later at a lower price and return them, pocketing the difference as profit.