The commissioner shall allow to the credit of an insurance company in the account of its financial condition only the assets that are or can be made available for the payment of losses in the state, but may credit any deposits of funds of the company set apart as security for a particular liability, or any deposits of funds of the company that are deposited for the purpose of meeting the requirements for doing business in another state or commonwealth. The commissioner may, in the commissioner's discretion, disallow stockholders' obligations of any description as part of the assets or capital of any insurance company, unless secured by competent collateral.