Tex. Gov't Code § 404.105

The trust company shall hold capital stock and reserve balances outside the treasury in an amount required by applicable regulatory bodies for eligibility for federal reserve services, for participation in a depository trust company, and as necessary to achieve its purposes under Section 404.103. The stock of the trust company is an authorized investment for state funds and shall be held by the comptroller, but the amount may not be more than $1 million.