Michael Eliasek
Analyst · Raymond James
Thank you, John. Our scale platform with around $7.5 billion of assets and undrawn credit continues to deliver solid performance in the current dynamic environment. Our experienced team consists of around 100 professionals, which represents one of the largest middle market investment groups in the industry.
With our scale, longevity, experience and deep bench, we continue to focus on a diversified investment strategy that spans third-party private equity sponsor related lending, direct non-sponsor lending, prospect sponsored operating and financial buyouts, structured credit and real estate yield and total return investing.
Consistent with past cycles, we expect during the next downturn to see an increase in secondary opportunities, coupled with wider spread primary opportunities with a pullback from other investment groups, particularly highly leveraged ones. This business diversity allows us to source a broad range and high volume of opportunities, then select in a disciplined and bottoms-up manner the opportunities we deem to be the most attractive on a risk-adjusted basis.
Our team typically evaluates thousands of opportunities annually and invests in a disciplined manner in a low single-digit percentage of such opportunities. Our nonbank structure gives us the flexibility to invest in multiple levels of the corporate capital stack with a preference for secured lending and senior loans. As of September 2021, our portfolio at fair value comprised 49.4% secured first lien debt, 16.5% other senior secured debt, 11.6% and subordinated structured notes with underlying secured first lien collateral, and 22.5% as a combination of unsecured debt, other debt and equity investments, resulting in 78% of our investments being assets with underlying secured debt benefiting from borrower pledged collateral.
Prospect's approach is one that generates attractive risk-adjusted yields. In our performing interest-bearing investments, we're generating an annualized yield of 11.6% as of September, down 0.1% from the prior quarter. We achieved an increase of 30 basis points from June 2020 despite a headwind from the past year decline in LIBOR, though we expect reasonable stability now due to our LIBOR floors. We also hold equity positions in certain investments that can act as yield enhancers or capital gains contributors as such positions generate distributions.
We've continued to prioritize senior and secured debt with our originations to protect against downside risk while still achieving above-market yields through credit selection discipline and a differentiated origination approach. As of September, we held 124 portfolio companies, stable with the prior quarter with a fair value of $6.4 billion, an increase of $229 million from the prior quarter.
We also continue to invest in a diversified fashion across many different portfolio company industries with a preference for avoiding cyclicality and with no significant industry concentration. The largest is 17.9%. As of September, our asset concentration in the energy industry stood at 1.3%. Our concentration in the hotel, restaurant and leisure sector stood at 0.4% and our concentration in the retail industry stood at 0%.
Non-accruals as a percentage of total assets stood at approximately 0.5% in September, down 0.1% from the prior quarter and down 0.4% from June 2020. Our weighted average middle market portfolio net leverage to 4.88x EBITDA, substantially below our reporting peers and down $0.13 from the June 2021 quarter.
Our weighted average EBITDA per portfolio company stood at $95.3 million in September, an increase of $6.2 million and 7% from June 2021 as we continue to achieve solid profit growth with our portfolio companies.
Originations in the September quarter aggregated $425 million. We also experienced $324 million of repayments and exits as a validation of our capital preservation objective, resulting in net originations of $101 million. During the September 2021 quarter, our originations comprised 94.5% middle market lending, 3.2% middle market lending and buyouts and 2.3% real estate.
To date, we have deployed significant capital in the real estate arena through our private REIT strategy, largely focused on multifamily workforce, stabilized yield acquisitions with attractive 10-plus year financing. NPRC, our private REIT, has real estate properties that have benefited over the past several years and more recently, from rising rents, showing the inflation hedge nature of this business segment, strong occupancies, high collections, suburban work-from-home dynamics, high-returning value-added renovation programs and attractive financing recapitalizations, resulting in an increase in cash yields as a validation of this income growth business alongside our corporate credit businesses.
NPRC as of September has exited completely 34 properties at an average IRR of 24.1%, with an objective to redeploy capital into new property acquisitions, including with repeat property manager relationships. We currently have multiple other property exits in process that we expect to add to our growing track record of positive realization.
Our structured credit business has delivered attractive cash yields, demonstrating the benefits of pursuing majority stakes, working with world-class management teams, providing strong collateral underwriting through primary issuance and focusing on attractive risk-adjusted opportunities. As of September, we held $751 million across 39 nonrecourse subordinated structured notes investments. These underlying structured credit portfolios comprised around 1,750 loans and a total asset base of around $16 billion.
As of September, the structured credit portfolio experienced a trailing 12-month default rate of 26 basis points, down 74 basis points from the prior quarter and representing 9 basis points less than the broadly syndicated market default rate of 35 basis points.
In the September quarter, this portfolio generated an annualized cash yield of 20.4% and GAAP yield of 12.2% with the difference representing an amortization of our cost basis. As of September, our subordinated structured credit portfolio has generated $1.37 billion in cumulative cash distributions to us, representing around 97% of our original investment.
Through September, we've also exited 10 investments totaling $287 million with an average realized IRR of 15.7% and cash-on-cash multiple of 1.45x. Our subordinated structured credit portfolio consists entirely of majority-owned positions. Such positions can enjoy significant benefits compared to minority holdings in the same tranche. In many cases, we receive fee rebates because of our majority position. As majority holder, we control the ability to call a transaction in our sole discretion in the future, and we believe such options add substantial value to our portfolio.
We have the option of waiting years to call a transaction in an optimal fashion rather than when loan asset valuations might be temporarily low. We as majority investor can refinance liabilities on more advantageous terms, remove bond baskets in exchange for better terms from debt investors in the deal and extend or reset the investment period to enhance value.
We completed 30 refinancings and resets since December 2017. So far in the current December 2021 quarter, we booked $226 million in originations and experienced $87 million of repayments for $139 million of net originations. Our originations have consisted of 100% middle market lending.
I'll now turn the call over to Kristin. Kristin?