The Japanese Government Pension Investment Fund (GPIF) announced in a December 3 press release that it has suspended stock lending activities “until further notice.”

The pension fund, the world’s largest with a portfolio worth $733 billion, said that part of its reason to suspend lending shares was down to the confusion it creates over ownership. GPIF suggested that lending shares “creates a gap in the period in which” the fund owns the shares and can be “inconsistent with the fulfillment of the stewardship responsibilities of a long-term investor,” as the pension fund would lose its voting rights on any shares it loans out.

The fund went on to highlight what it called “inconsistencies” in the way stock lending works. GPIF claimed that the current scheme “lacks transparency” over who is the “ultimate borrower” of a stock is after a short seller sells the shares loaned to them. The fund added the “purpose they are borrowing the stock” was another concern, with a third party holding the voting rights and possibly using them to vote against proposals GPIF approves or opposes.

If other institutional investors follow in GPIF’s footsteps, it could make it harder for short sellers to make their bets as these are the main users of borrowing facilities.

GPIF’s wariness of stock lending arrives in a year that has seen a growing uneasiness toward short sellers. On April 16, German watchdog BaFin filed criminal complaints against two Financial Times journalists and about 10 short sellers who questioned Wirecard’s accounting, an incident which Muddy Waters’ founder Carson Block described as a “global war against truth,” to Reuters.

The news was applauded by Tesla founder Elon Musk, who said GPIF’s action was “the right thing to do,” adding that “short selling should be illegal.” Musk’s Tesla has been targeted by a host of short sellers, including titans of the industry Greenlight Capital and Kynikos Associates. According to Activist Insight Shorts, Tesla is currently the most-shorted stock by activist short sellers.

GPIF has not ruled out returning to the stock lending space in the future but clarified that “improvements” to “enhance transparency” would need to be introduced first. The fund added that while it is suspending its stock lending, it will continue to loan shares in the debt securities market.