California Code, Government Code - GOV § 31699.6

(a) The postemployment health benefits fund board shall determine the investments of the postemployment health benefits fund and may delegate this function to the extent consistent with its fiduciary responsibilities, including delegating this function to the retirement system board.

(b) The postemployment health benefits fund board may offer different investment pools to be chosen by the public agencies and their trust funds that participate in the postemployment health benefits fund.

(c) To the extent allowed by California law and federal law, including, but not limited to, federal tax and securities law, the postemployment health benefits fund board may invest the assets that it holds, and the retirement system board may invest the assets that it holds, in investment pools established under this article, and each of those boards may combine or commingle, for investment purposes only, the assets that it holds with the assets held by the other board.  The postemployment health benefits fund board and the retirement system board may take any and all actions necessary or appropriate to implement that combination or commingling, including, but not limited to, unitizing the investments held for retirement purposes.

(d) The retirement system board may invest the assets that it holds for retirement purposes, and the postemployment health benefits fund board may invest the assets held in the postemployment health benefits fund in the same or similar investments by parallel investing rather than commingling the assets for investment.