Elon Musk's proposed $1 trillion compensation package with Tesla (TSLA.US) is facing resistance as the California Public Employees' Retirement System (CalPERS), the largest U.S. public pension fund, plans to vote against it. This could jeopardize what would be the highest executive pay package in corporate America.

CalPERS holds approximately 5 million Tesla shares. A spokesperson for the fund stated via email, "Tesla's proposed CEO compensation package is orders of magnitude higher than those of peer companies. It also further concentrates power in the hands of a single shareholder."

Musk has been pushing for approval of the pay package ahead of a crucial shareholder vote at Tesla's annual meeting in Austin on November 6. The world's richest man urged investors to support the plan during the company's earnings call this month, criticizing shareholder advisory firms opposing it.

The $1 trillion compensation agreement, spanning 10 years, requires Musk to meet specific performance milestones to receive the full payout. Additionally, it grants him more shares, potentially increasing his stake in the automaker to at least 25%.

Musk's past compensation plans have also faced scrutiny. Last year, CalPERS CEO Marcie Frost stated the pension fund's concerns over his proposed $56 billion pay package. The fund had previously opposed a 2018 deal worth over $50 billion, which was ultimately voided by a Delaware court. Tesla is currently appealing that ruling.