More importantly, we continue to grow subscription services revenues which reflect the recurring revenues from our expanding cloud business. In Q4, subscription services revenues were $21.5 million, which is an increase of 23% year-over-year, and $81.2 million for the full year, an increase of 34% year-over-year. Current subscription billings, which reflect new cloud bookings, grew 33% in the fourth quarter to $41.3 million and $94.8 million for the full year, a 23% increase year-over-year, which was our 15th straight quarter of double digit growth in cloud bookings. Q4 was an important milestone for us, where for the first time in both Q4 and for the full year, our subscription services revenues were higher than our product license revenues.
This was a significant achievement to show the continued progress in our transition to stronger recurring revenues in the cloud. As I mentioned before, we expect the mix of revenue will continue to shift from product license to subscription services revenues in 2024 as we focus on delivering AI-based products to our customers in the cloud. Moving to costs, total non-GAAP expenses were $148 million in the fourth quarter, 52% lower compared to the fourth quarter of 2022. Bitcoin impairment charges for the quarter were $39 million compared to $198 million in Q4 of last year. Total non-GAAP expenses excluding bitcoin impairment were $108 million in the fourth quarter down 3% year-over-year. While we’re spending more on cloud hosting costs as we grow our cloud business, we have been able to offset those increases with cost reductions in corporate overhead and while optimizing headcount, which was down 10% year-over-year.
We reported a total non-GAAP operating loss in the fourth quarter of $23 million, of which, the loss on the bitcoin impairment was $39 million in the quarter. For the fourth quarter, we reported GAAP net income of $89 million, which included a $150 million tax benefit, primarily due to changes in the valuation allowance on our deferred tax asset, directly related to our bitcoin holdings. And at the end of Q4, fair market value of bitcoin as of December 31st was above our aggregate cost basis, resulting in a release of the previously established valuation allowance and a corresponding non-cash tax provision benefit. Turning to our bitcoin strategy, we had an extremely successful Q4 adding more bitcoin to our holdings, acquiring 30,905 bitcoins in the quarter, the largest single quarter bitcoin holdings increase since Q4 of 2020.
After the end of the quarter, we purchased an additional 850 bitcoins using $37 million of excess cash. And as of February 5th, 2024, the company held a total of 190,000 bitcoins, acquired for an aggregate cost of $5.93 billion, or $31,224 per bitcoin. Bitcoins purchased through excess cash from the software business are held at MicroStrategy, the parent entity, and are secured under our 2028 secured notes. As of yesterday, there were 16,931 bitcoins held at MicroStrategy. Bitcoins acquired through proceeds from capital markets activities after the issuance of our senior secured notes, which include equity and debt issuances, are held at MacroStrategy, which is a wholly owned subsidiary of MicroStrategy. We hold 173,069 bitcoins, representing 91% of our total bitcoin holdings or over $7.3 billion in current market value at the MacroStrategy level, all of which are currently unrestricted and unencumbered, providing us with optionality to potentially leverage this strategic asset in the future.
In Q4, we purchased a total of 30,555 bitcoins for $1.2 billion using net proceeds from our ATM program. As noted a moment ago, these bitcoins are held at MacroStrategy and remain unencumbered. In Q4, we also purchased an additional 350 bitcoins for $13.4 million using excess cash from operations, which are held at MicroStrategy. And subsequently, in January 2024, we used additional excess cash from operations to purchase an additional 850 bitcoins for $37 million, which are also held at MicroStrategy. Our commitment to our bitcoin strategy remains unchanged and unwavering, and we plan to add more bitcoin over time using our excess cash from operations, as well as proceeds from any capital markets activities. MicroStrategy is the largest corporate holder of bitcoin in the world and we have remained committed to our bitcoin acquisition strategy with the highest conviction, with a consistent track record, long-term focus, and a strong risk managed approach to acquiring and holding more bitcoin on our balance sheet.
Turning to Slide 15, we saw bitcoin outperform the US equity markets in 2023. As of December 31, 2023, the carrying value of our bitcoin holdings is approximately $3.6 billion compared to approximately $8 billion in market value based on the bitcoin price as of the last day of the quarter. Year to date, the market value of our bitcoin holdings is approximately $8.1 billion, which is significantly above our average purchase price of approximately $31,200. In late December, FASB approved a change in accounting rules for certain digital assets, including bitcoin, to be measured using fair value accounting. We are delighted by FASB’s expeditious move to create more transparent reporting, and we are encouraged by the continuing maturity of the regulatory environment surrounding bitcoin and we hope these enhanced accounting rules will serve as a positive on-ramp for other corporates to adopt bitcoin as a treasury reserve.
The new accounting rule requires companies holding digital assets, including bitcoin, to adopt fair value accounting treatment by Q1 of 2025. And while we have not yet elected to early adopt the new accounting standard, which was only just finalized late in the fourth quarter, we continue to evaluate the timing along with accounting and tax impacts of adoption. If we elect to adopt the new accounting standard in 2024, we estimate that our 2024 beginning bitcoin holdings value would be marked up to a fair value of approximately $8 billion as of January 1st, 2024. As Phong mentioned earlier, we have effectively used excess cash flows to grow our bitcoin holdings. At the inception of our bitcoin balance sheet strategy in 2020, we allocated a substantial portion of our cash reserves generated over many previous years into bitcoin, acquiring over 43,000 Bitcoin for $595 million.
Beyond that initial acquisition, we have continued to acquire an average of $40 million of bitcoin each year with excess cash on our balance sheet, totaling approximately 3,500 bitcoins since 2022. Our ability to leverage cash from operations enables us to increase our bitcoin holdings in a manner that we believe is accretive to our shareholders. And in total, we have issued approximately $726 million of excess cash to acquire more bitcoin, accounting for approximately 48,000 bitcoin added to our balance sheet, or about 25% of our total bitcoin holdings. Now turning to our capital markets activities, also since the inception of our bitcoin strategy, we have raised $2.2 billion of debt through senior secured notes and convertible notes with an attractive blended interest rate of approximately 1.6%, with the earliest maturity not until 2025.
Leverage remains a key component of our active capital management strategy, which when intelligently deployed enables us to accrete more bitcoin on our balance sheet at an attractive cost. We will continue to actively monitor the capital markets, evaluating liability management opportunities to manage our debt maturities as well as opportunities to raise additional debt in the future. In addition to raising debt, we have demonstrated a solid track record of issuing permanent equity capital in a manner that we believe has been accretive to our shareholders. Since the third quarter of 2021, we have raised a total of $3.1 billion in proceeds through our at-the-market or ATM programs, with the average price of approximately $457 per share across total equity raised.
In Q4 of last year, we accelerated the execution of our current ATM program and raised $1.2 billion in aggregate net proceeds. And in Q4 alone, we issued approximately 2.27 million shares of Class A common stock [indiscernible] approximately $138 million of capacity remaining under our current program. As we have done in the past, we will continue to carefully evaluate the most accretive use of proceeds from the sale of equity to be incremental value for our shareholders. The primary use of proceeds from the sale of equity to date has been to acquire additional bitcoin. But we also use proceeds of our ATM program to prepay the $250 million bitcoin back loan in Q1 of 2023, which generated a $45 million gain on extinguishment. Our capital allocation strategy continues to be focused on increasing the value generated from our balance sheet through the addition of more bitcoin, while managing our debt very carefully.
Also, at the end of the fourth quarter, we had $46.8 million in cash on our balance sheet, which is sufficient overall liquidity to manage our ongoing operating needs. 2023 was an extremely successful year for us where we generated approximately $5.8 billion of incremental value from both the increase in the price of bitcoin of our existing holdings, as well as through our strategic use of equity capital markets activities. We began the year with 132,500 bitcoins on our balance sheet with a market value of approximately $2.2 billion. As bitcoin prices increased from approximately $16,500 to approximately $42,500 by the end of the year, it resulted in an increase of over $3.4 billion in value based on our bitcoin holdings at the start of the year.
In addition to the price appreciation of bitcoin we held as of the beginning of the year, MicroStrategy’s issuance additional equity and use of excess cash from operations to purchase even more bitcoin in 2023 led to an increase of an additional $1.9 billion in value of our bitcoin holdings. In total, we add an additional 56,650 bitcoins to our balance sheet at an average price of $33,580, which generated an approximately $500 million of value from the increase in the price of bitcoin after those purchases were made. Again, overall, 2023 was a tremendously successful year, and taking into account our purchases and appreciation of our holdings, we increased the value of our bitcoin holdings by 267% to $8 billion over the course of the year. While the overall market benefited from the increase in Bitcoin prices, well, we believe our intelligent use of leverage and excess cash to acquire more bitcoin, as well as our equity capital market strategy contributed $2.4 billion of incremental value for our balance sheet, demonstrating our track record of generating value for our shareholders.
This slide shows an illustrative example of how responsible and intelligent leverage can be used to boost returns when bitcoin prices are increasing. The baseline returns of any long bitcoin strategy benefit from spot bitcoin price appreciation. Bitcoin ETPs also benefit from this offset, of course, by the management fees that are charged for those products. Leverage provides us the opportunity to generate higher returns if price increases. In this illustration, assuming bitcoin price reaches $250,000, keeping bitcoin count constant, Spot Bitcoin without leverage would return approximately 480%. In this example, adding leverage to acquire more bitcoin would return between 660% to 740%, depending on the amount of leverage further boosting returns compared to simply holding spot.
