Our investment portfolio has limited exposure to structured asset-backed securities. As of June 30, 2023, we had $136 million in ABS, which are pools of assets collateralized by cash flows from several types of loans, including home equity, credit cards, autos and structured bank loans in the form of collateralized loan obligations (CLOs).
As of June 30, 2023, we had $116 million in commercial mortgage-backed securities and $372 million in mortgage-backed securities backed by government sponsored enterprises (GSEs - Freddie Mac, Fannie Mae and Ginnie Mae). Excluding the GSE-backed MBS, our exposure to ABS and CMBS was 7.0 percent of our investment portfolio at quarter end.
We had $1,148 million in corporate fixed income securities as of June 30, 2023, which includes $110 million invested in a high-yield credit strategy. This high-yield portfolio consists of floating rate bank loans and bonds that are below investment grade in credit quality and offer incremental yield over our core fixed income portfolio.
The municipal portfolio includes approximately 56 percent taxable securities and 44 percent tax-exempt securities. Approximately 90 percent of our municipal bond portfolio maintains an ‘AA’ or better rating, while 100 percent of the municipal bond portfolio is rated ‘A’ or better.
Securities within the equity portfolio are well diversified and are primarily invested in broad index exchange traded funds (ETFs). Our actively managed equity strategy has a preference for dividend income and value oriented security selection with low turnover, which minimizes transaction costs and taxes throughout our long investment horizon.
As of June 30, 2023, our equity portfolio had a dividend yield of 2.0 percent, compared to 1.5 percent for the S&P 500 index. Because of the corporate dividend-received-deduction applicable to our dividend income, we pay an effective tax rate of 13.1 percent on dividends, compared to 21.0 percent on taxable interest and 5.3 percent on municipal bond interest income. The equity portfolio is managed in a diversified and granular manner, with 85 individual securities and four ETF positions. No single company exposure in the equity portfolio represents more than 1 percent of invested assets.
Other invested assets include investments in low income housing tax credit and historic tax credit partnerships, membership in the FHLBC and investments in private funds.
We had $55 million of investments in unconsolidated investees at June 30, 2023, compared to $58 million at December 31, 2022.
Our investment portfolio does not have any exposure to derivatives.
Our capital structure is comprised of equity and debt outstanding. As of June 30, 2023, our capital structure consisted of $200 million in long-term debt and $1.4 billion of shareholders’ equity. Debt outstanding comprised 13 percent of total capital as of June 30, 2023. Interest and fees on debt obligations totaled $4 million for the first six months of 2023 and 2022. We incurred interest expense on debt at an average annual interest rate of 3.89 percent during the first six months of 2023 and 2022.
We paid a regular quarterly cash dividend of $0.27 per share on June 20, 2023, an increase of $0.01 from the prior quarter. We have increased dividends in each of the last 48 years.
Our three insurance companies are subsidiaries of RLI Corp, with RLI Ins. as the first-level, or principal, insurance company. At the holding company (RLI Corp.) level, we rely largely on dividends from our insurance subsidiaries to meet our obligations for paying principal and interest on outstanding debt, corporate expenses and dividends to RLI Corp. shareholders. As discussed further below, dividend payments to RLI Corp. from our principal insurance subsidiary are restricted by state insurance laws as to the amount that may be paid without prior approval of the insurance regulatory authorities of Illinois. As a result, we may not be able to receive dividends from such subsidiary at times and in amounts necessary to pay desired dividends to RLI Corp. shareholders. On a GAAP basis, as of June 30, 2023, our holding company had $1.4 billion in equity. This includes amounts related to the equity of our insurance subsidiaries, which is subject to regulatory restrictions under state insurance laws. The unrestricted portion of holding company net assets is comprised primarily of investments and cash, including $262 million in liquid assets, which was elevated by the cash proceeds received from the sale of Maui Jim. Unrestricted funds at the holding company are available to fund debt interest, general corporate obligations and dividend payments to our shareholders. If necessary, the holding company also has other potential sources of liquidity that could provide for additional funding to meet corporate obligations or pay shareholder dividends, which include a revolving line of credit, as well as access to capital markets.