Dwayne Hyzak
Analyst · Robert Dodd with Raymond James
Thanks, Todd. As Vince and Todd previously mentioned, we are happy to report significant increases in both total investment income and net investment income and significant realized gains for the first quarter ended March 31, 2012.
Total investment income for the first quarter increased by 54% over the same period in 2011 to a total of $20.6 million for the quarter. This increase was primarily driven by increased amounts of interest income associated with higher average levels of portfolio debt investments and interest-bearing marketable securities investments. The increase in investment income in the first quarter also included approximately $1.8 million of nonrecurring investment income associated with repayment and financing activities associated with 2 lower middle market portfolio investments and an increase of approximately $300,000 in investment income associated with higher levels of accelerated prepayment activity with certain middle market debt investments and marketable securities investments.
First quarter 2012 operating expenses, excluding noncash share-based compensation expense, increased by $1.6 million over the first quarter of 2011 to a total of $7.1 million. The operating expense increase was primarily due to higher interest expense as a result of the issuance of $40 million of SBIC debentures after the beginning of the first quarter of 2011 and increased borrowing activity under our credit facility. The increase also included higher accrued compensation and other operating expenses related to the increase in investment income and portfolio investment activity compared to the first quarter of prior year.
The ratio of total operating expenses, excluding interest expense, as a percentage of average total assets, which we believe is a key metric in evaluating our operating efficiency, was 2% on an annualized basis for the first quarter of 2012 compared to 2.5% on an annualized basis for the first quarter of 2011 and 2.2% for the full year ended December 31, 2011.
Before providing more details on our operating results, I want to remind everyone why in our earnings release and conference call comments, we reference distributable net investment income, which is net investment income excluding the impact of noncash share-based compensation expense, when discussing our profitability. We utilize this measure as we believe it is an important disclosure for analyzing our financial performance since the share-based compensation expense does not require settlement in cash and does not reduce our taxable income. In addition, the economic impact of restricted stock issued is already accounted for in our earnings per share calculations as the restricted shares are considered outstanding when granted. As a result, we believe that distributable net investment income is an important measure when evaluating our operating performance in comparison to our dividends.
Distributable net investment income for the first quarter of 2012 increased by 71% to $13.4 million or $0.50 per share in comparison to $7.8 million or $0.40 per share for the same period in the prior year. Our distributable net investment income for the first quarter exceeded our dividends paid by $0.095 and, together with our realized gains for the first quarter, resulted in estimated spillover taxable income of approximately $23.8 million or $0.88 per share at March 31, 2012.
While the dollar amount of distributable net investment income increased by 71% over the prior year, the per share percentage increase was 25% due to the higher average number of shares outstanding compared to the corresponding period in prior year primarily due to the impact of the March and October 2011 follow-on stock offerings. All other first quarter 2012 per share measures were similarly impacted by the higher weighted average shares outstanding.
Distributable net realized income for the first quarter of 2012 was $21.6 million or $0.80 per share, which represented an increase of $13.8 million or a percentage increase of 175% in comparison to the first quarter of prior year. This increase was due to the higher level of distributable net investment income during the first quarter of 2012 and the total net realized gains from investment during the first quarter totaling $8.1 million.
The net realized gain from investments was primarily due to realized gains totaling $9.2 million on a partial exit of our equity investments in Drilling Info, $1.7 million on the full exit of our investments in NTS Holdings and net realized gains totaling $1 million on our middle market and marketable securities investments. These realized gains were partially offset by realized losses totaling $3.8 million on the full exit of equity investments in one lower middle market portfolio company and a loss on a debt investment related to the full exit of another lower middle market portfolio company.
As Vince previously mentioned, during the first quarter of 2012, we recognized $11.6 million of net unrealized appreciation on our portfolio investments. This increase included net unrealized appreciation totaling $7.9 million in our lower middle market portfolio resulting from appreciation on 19 portfolio companies totaling $9.6 million, partially offset by depreciation on 5 portfolio companies totaling $1.7 million, and $3.7 million of net unrealized appreciation on our middle market investment portfolio.
The net change in unrealized appreciation for the first quarter also included approximately $7.1 million of accounting reversals of net unrealized appreciation related to the net realized gains recognized during the first quarter, approximately $300,000 of net unrealized appreciation related to our SBIC debentures held by Main Street Capital II and unrealized appreciation of approximately $100,000 related to Main Street's investment in the affiliated Investment Manager.
As we previously indicated on our fourth quarter of 2011 conference call, during the first quarter of 2012, we acquired all of the limited partnership interest of our subsidiary SBIC, Main Street Capital II, that were not previously owned by Main Street. These acquisitions were accretive to both net investment income and net asset value, and we believe the elimination of this minority interest provides for better clarity in our financial reporting to our shareholders in future periods.
Now let me finish with a few portfolio statistics, all as of March 31. In our lower middle market portfolio, we have 53 investments representing approximately $388.1 million of fair value as of March 31 or approximately 20.4% above the cost basis of approximately $322.3 million. Consistent with our investment strategy, approximately 77% of our lower middle market portfolio investments at cost were in the form of secured debt investments, and approximately 98% of those debt investments held the first-lien security position. The weighted average effective yield on our lower middle market portfolio debt investments as of March 31, 2012, was 14.9%. We held equity positions in 92% of our lower middle market portfolio companies, with an average fully diluted equity ownership of approximately 33%. The fair value of our lower middle market portfolio company equity investments as of March 31, 2012, was approximately 195% of the cost of such equity investments. As Vince previously mentioned, at the lower middle market portfolio level, the weighted average net senior debt-to-EBITDA ratio was 2:1 or 2.4:1 including portfolio company debt, which is junior in priority to Main Street's debt position. We expect that these lower middle market portfolio level statistics on a same-store basis should generally continue to improve over time based upon the continued favorable operating performance of our portfolio companies and as our companies naturally delever.
Based upon our internal investment rating system, with a rating of 1 being the highest and 5 being the lowest, the weighted average investment ranking for our lower middle market investment portfolio was 2.1 on March 31, 2012, compared to 2.2 on December 31, 2011. And during the quarter, we had 4 portfolio companies improve their rating and one portfolio company decrease its rating from prior quarter.
You'll note that in our earnings release and Form 10-Q for the first quarter, we have revised our investment portfolio descriptions to include a new middle market category, which replaces our historical private placement investment portfolio category and also includes a significant portion of our historical marketable securities investments, which are investments in middle market companies. We made this change in an effort to provide our shareholders with additional clarity regarding the differences between our middle market and marketable securities investments.
In general, going forward, our middle market investments will represent debt investments in middle market businesses that are generally larger in size than our lower middle market portfolio of companies.
In our middle market portfolio, we had investments in 62 companies, representing approximately $251 million of fair value as of quarter end, and we're generating a weighted average yield of approximately 9.2%. Main Street's middle market portfolio investments are primarily in the form of debt investments, and approximately 86% of our middle market portfolio debt investments at cost held the first-lien security position, with most of the remaining investments representing second-lien secured investments. The weighted average revenues for the 62 middle market portfolio company investments was approximately $476 million.
The total investment portfolio fair value at March 31, 2012, was approximately 111% of the related cost basis, and we had no portfolio investments on nonaccrual status and 2 fully impaired portfolio investments representing approximately 0.9% of the total investment portfolio at cost.
With that, I will now turn the call back to the operator so that we may take any questions.