For the fourth quarter, we reported non-GAAP operating income of $3.3 million or $0.06 per share.
For the full year, we reported a non-GAAP operating loss of $27.7 million, attributable to the pre-tax net underwriting loss of $45.7 million, associated with the tail policy issued to a large national healthcare account and a pre-tax $10 million IBNR reserve related to the pandemic, both of which were recorded in the second quarter.
For the fourth quarter, our consolidated net loss ratio was 74.9%, a significant quarter over quarter decrease primarily due to the effects of the large national healthcare account in the year ago quarter.
But most importantly, also reflected our reunderwriting and rate strengthening efforts over the last 12 months.
For the year, the net loss ratio was 83.4%, a 5.6 percentage point decrease primarily due to favorable reserve development and a reduction to the current accident year net loss ratio, driven by improvements made in our Specialty P&C segment.
Our consolidated underwriting expense ratios for the quarter and for the year of 30.9% and 30% respectively were relatively unaffected by our contracting topline revenue from our reunderwriting efforts, which demonstrates that the strategic initiatives to improve our underlying expense structure have taken hold.
From an investment perspective, our consolidated net investment result increased quarter-over-quarter to $26.3 million, driven by $10.1 million of income from our unconsolidated subsidiaries.
We invest in various LPs and LLCs and the results of those investments are typically reported to us on a 1/4 lag, accordingly, the earnings from unconsolidated subsidiaries in the current quarter represent the recovery in value of our LPs and LLCs in the third quarter.
Consolidated net investment income was $16.1 million in the quarter, down from the year ago period primarily due to a decrease in our allocation to equities and lower yields from our short-term investments and corporate debt securities, given the actions taken by the Federal Reserve to reduce interest rates in response to COVID-19.
In addition, gross premiums written in the quarter reflected renewal timing differences of $4.6 million dollars in our Specialty business, and the non-renewal of a $2.8 million dollar policy in our Standard Physicians business.
Retention for the full year was 79% and reflects the reunderwriting in specialty and rate strengthening efforts and standard positions over the past 12 months.
In addition to higher premium retention in the quarter, we achieved renewal price increases of 8% in the segment, driven by price increases in both our Standard Physician and Specialty business of 10%.
For the full year, we achieved renewal price increases of 9% attributable to increases in the Specialty and Standard Physicians business of 15% and 11% respectively.
New business writings were $5.3 million in the quarter compared to 4.6 million in the fourth quarter of 2019, driven by our Medical Technology Liability business.
Year-end new business writings were $23 million, compared to $43 million in 2019 which reflects careful risk selection, disciplined underwriting evaluation, and the impact of slower submission activity due to market disruptions from the pandemic.
The current accident year net loss ratio decreased 6.3 percentage points year-over-year, exclusive of the impact of the large national healthcare account in 2019 and 2020 and posting of the COVID IBNR reserve in the second quarter.
We established a pre-tax $10 million IBNR reserve in the second quarter related to reported incidents.
Despite the challenges of the current loss environment, we recognized net favorable development of $6.8 million and $27.5 million in the fourth quarter and full year respectively.
The Specialty Property & Casualty segment reported expense ratios of 23.8% and 23% in the fourth quarter and full year respectively.
Incremental improvements of 1.4 and 1.1 percentage points as compared to the same periods of 2019.
This result was achieved despite lower net earned premiums and $4 million of one-time charges during the year related to restructuring.
As a result of organizational structure enhancements, office consolidations and reductions in staff, we achieved expense savings of approximately $12 million in 2020.
The current reinsurance market continues to firm as a result of social inflation and severity claim trends, via successful October renewal of our reinsurance treaty and mitigated potential significant cost increases by increasing our retention from $1 million to $2 million for -- [Technical Issues] liability and Medical Technology Liability businesses.
The Workers' Compensation Insurance segment produced income of $6 million and a combined ratio of 97.8% for 2020, including income of $2.1 million and a combined ratio of 96.3% for the fourth quarter.
During the quarter and full year, the segment booked $47 million and $247 million of gross premiums written respectively, representing decreases of 13.6% and 11.4% compared to the same periods in 2019.
Renewal pricing in 2020 decreased 4% for both the quarter and full-year, reflecting the continued competitive pressures in our underwriting territories despite COVID-19 and the associated economic conditions.
Premium renewal retention was 82% for the 2020 quarter and 84% for the year, both improvements compared to 76% and 83% for the same periods in 2019.
New business writings decreased quarter over quarter to point $4.4 million dollars in 2020, compared to $5.5 million in 2019.
And for the full year were $27.4 million in 2020 compared to $30.8 million in 2019.
Audit premium for the fourth quarter of 2020 resulted in additional premium to the company of approximately $700,000 compared to $2.2 million for 2019, and for the year, was additional premium of $700,000 compared to $5.7 million in 2019.
The 2020 accident year loss ratio was 69% for the year, compared to 68.4% in 2019.
Net favorable loss reserve development for the quarter was $2 million in 2020 compared to $4.4 million dollars in 2019, and for the full year was $7 million versus $7.8 million in 2019.
Reported claim frequency for non-COVID claims decreased 35% during the pandemic, with only $2.2 million of gross undeveloped incurred losses at the end of 2020 from the currently reported 1,375 COVID claims.
Further, through the end of January 2021, we closed 87% of the 2020 reported COVID claims received to date, indicative of the shorter tailed nature of workers' compensation insurance compared to healthcare professional liability.
Our claims professionals' continue to function effectively while working remotely, closing 61% of 2019 and prior claims during 2020, consistent with historical claim closing rates.
Turning to expenses, the underwriting expense ratio in the quarter was 32.7% compared to 29.8% in 2019 reflecting the decrease in net premiums earned.
The underwriting expense ratio decreased 2.5 percentage points from the third quarter of 2020 due to our restructuring efforts discussed on our November earnings call, and to a lesser extent, the associated one-time expense of $900,000 included in the third quarter.
For the 2020 year, the expense ratio was 32.9% compared to 30.4% in 2019.
Turning now to the Segregated Portfolio Cell Reinsurance segment, we reported income of $1.6 million for the quarter and$4.4 million dollars for all of 2020.
The SPC resegment recorded favorable development of $9 million in the fourth quarter of 2020 compared to $2.3 million in 2019, and for the full year was $16.6 million dollars versus $10.1 million in 2019.
As of December 31, 2020, we had 1,090 reported COVID claims for this segment with $1 million of gross undeveloped incurred losses.
Our participation in the results of Syndicate 1729 and 6131 let us to record a loss of just under $1 million in the quarter.
The fourth quarter loss, combined with our reduce participation in Syndicate 1729 for the 2020 underwriting year, contributed to overall lower income of approximately $2.1 million for the year.
Losses on these storms and other natural catastrophes in the last three months of 2020 lead us to expect the segment loss in our first quarter of approximately $2.5 million.
For the 2021 underwriting year, we have further reduced our participation in Syndicate 1729 from 29% to 5%.
Additionally, we reduced our participation in Syndicate 6131 from 100% to 50% for the 2021 underwriting year.
Before we open the call to questions, I'll note that the meaningful improvements we've made in the past 12 months go a long way toward our goals of operational excellence and sustainable profitability.

Summary:
For the fourth quarter, we reported non-GAAP operating income of $3.3 million or $0.06 per share.