Overall, we are extremely pleased with the continued acceleration of our improving operating trends in the third quarter, which exceeded our initial expectations and resulted in more than a 25% increase in RevPAR from the second quarter.
Demand growth accelerated broadly during the quarter as we sold nearly 7% more room nights in the third quarter than we did in the second quarter, peaking during a historically strong summer travel season in July when occupancy in the portfolio was above 72%.
Although August demand pulled back modestly as expected, we saw a reacceleration in the back half of September when occupancy averaged nearly 70% during the last two weeks of the quarter.
Negotiated room revenue increased approximately 28% in the third quarter over the second quarter.
We reported third quarter pro forma RevPAR of $98, which was more than double our RevPAR in the third quarter of last year and was 24% lower than what was achieved in the third quarter of 2019, a significant improvement from the first half of the year when RevPAR was nearly 43% lower in the second quarter and 59% lower in the first quarter than the comparable 2019 periods.
As ADR across our portfolio increased 19% compared to the second quarter, and weekday ADR growth outpaced weekend growth by nearly 200 basis points.
Average rates in our urban portfolio increased 24% from the second quarter, and weekday urban ADR grew 27% from the second quarter, which encouragingly reflects some level of rate accretive remixing of our business with corporate travel.
Weekend occupancy was an impressive 80% during the third quarter and averaged 82% in July and September as the recovery continues to clearly be led by exceptionally strong leisure demand.
However, mid-week occupancy also continues to steadily improve, climbing to 64% during the first quarter, a full five percentage points higher than the second quarter and the gap between weekday and weekend occupancy continues to narrow.
During the third quarter, we completed the previously announced acquisition of the newly built 110 guestroom residence in Steamboat Springs for $33 million.
The extended-stay hotel is the newest hotel in Steamboat, one of only six other hotels that have opened in the market since the year 2000, and the first Marriott-branded extended stay product in the market.
Since acquisition, the hotel has performed exceptionally well, generating occupancy and RevPAR of nearly 87% and $161, respectively, and hotel EBITDA margin of 49% for the third quarter.
On an annualized basis, this equates to a 9% net operating income yield and less than three months of ownership, despite the hotel having been open for less than one year.
During the third quarter, we invested approximately $4.2 million in our portfolio on items primarily related to planned maintenance capital.
We expect to spend between $15 million and $20 million in capital expenditures for the year on a consolidated basis.
And between $14 million and $19 million on a pro rata basis.
During the third quarter, our resort and other nonurban hotels continued to show robust sequential improvement with RevPAR growth of 12% relative to the second quarter of this year, and a nominal RevPAR value exceeding $100.
This subset of the portfolio illustrates Summit's diversification and broad exposure to the overall lodging recovery as ADR increased 13% to $135 relative to the second quarter on stable occupancy of 74%.
RevPAR at our urban hotels increased 43% from second quarter 2021 to approximately $94, primarily on the strength of rate, which increased 24%.
As an additional point of reference, in third quarter 2020, our urban portfolio posted a RevPAR of $37, further evidence of the strong rebound experienced year-over-year.
As a final point on our urban portfolio, we believe business travel is now in the early stages of its recovery as urban midweek occupancy increased 10 percentage points from the second quarter to 57%, and ADR increased more than $30 to $144 or a 27% increase for the quarter.
This translates to a RevPAR growth rate of 54% versus second quarter for the urban portfolio.
Full week group RevPAR for the company's total portfolio increased by 76% relative to second quarter 2021, while weekday group RevPAR increased by 100% during the same time frame.
Similarly, full week negotiated RevPAR increased by 28% relative to second quarter, while weekday negotiated RevPAR increased by 32%.
For example, transient room nights booked within 24 hours this day, declined from 23% of total bookings in the second quarter to 21% of bookings in the third quarter.
But importantly, nights booked more than 30 days out, increased by 19% during that same period.
From a cash flow perspective, continued growth in demand, combined with thoughtful expense management, enabled Summit to generate positive corporate cash flow of $18.5 million in Q3, which was more than triple the corporate cash flow of Q2 2021.
Pro forma hotel EBITDA was $38.8 million in the third quarter, exceeding the previous two quarters combined by approximately $5 million.
Operating costs per occupied room declined nearly 10% compared to 2019, which drove third quarter gross operating profit margin and hotel EBITDA margin to an impressive 47% and 35%, respectively.
We continue to operate our hotels utilizing a very lean staffing model, which consists of approximately '19 FTEs on average or slightly more than 55% of free pandemic staffing levels.
Despite these challenges and increasing occupancy levels, our asset management team has done a great job controlling operating expenses, leading to hotel EBITDA retention of 54% when compared to the third quarter of 2019.
Additionally, we accessed the capital markets in August, taking advantage of a favorable preferred equity market with the issuance of $100 million of five and seven, eight Series A perpetual preferred paper.
Proceeds from this opportunistic offering were used to accretively refinance our $75 million, 6.45% Series B preferred stock and to reduce the outstanding balance on our November 2022 term loan to its current balance of $62 million.
We're thrilled to announce the acquisition of a 27 hotel portfolio from NewcrestImage, which is comprised of approximately 3,700 guest rooms located across 10 high-growth Sunbelt markets in Texas, Oklahoma City and New Orleans.
These hotels are highly complementary to our existing portfolio with premium brand affiliations, excellent locations in strong markets and comprise a relatively new portfolio with approximately 70% of the guest rooms opening since 2015 and more than 1/3 of the guestrooms built in the last three years.
The hotel portfolio's allocated value of $776.5 million equates to approximately $209,000 per key, which reflects a significant discount to replacement costs and results in a stabilized NOI yield of 8% to 8.5%, including underwritten capital expenditures.
Our increased exposure to Sunbelt markets, which will be approximately 60% of our pro forma room count, positions the combined hotel portfolio to benefit from the favorable migration patterns, labor dynamics, corporate relocation activity, return to office trends and general pro business climates in these markets.
In addition to the hotel portfolio, we will be acquiring two parking structures, totaling approximately 1,000 parking spaces that serve two triplex hotel clusters, one in Downtown Dallas and the other in the emerging mixed-use development of Frisco Station, a thriving North Dallas suburb.
Our joint venture with GIC will acquire the assets for a total consideration of $822 million, and we will finance the investment with a new $410 million credit facility.
GIC's 49% equity interest will be a cash contribution totaling approximately $208 million, and our 51% controlling interest will come from a combination of common and preferred op units.
We will issue 15.9 million shares of common op units valued at $160 million.
Based on our common stock's 10-day [Indecipherable] as of Tuesday's closing price equal to $10.09 per share.
NewcrestImage ownership will be approximately 13% of our total shares outstanding.
The preferred op units totaling $50 million will be issued at a standard $25 par value and pay an annual coupon equal to 5.25%.
The transaction would increase our combined room count by over 30% and our total enterprise value by approximately 20%.
Acting as a general partner, on behalf of the joint venture, we will continue to earn fees for our asset management services and expect our stabilized fee stream earned through the joint venture will cover approximately 17% of our in-place cash corporate G&A.
The utilization of common and preferred op units for our 51% equity interest will preserve nearly all of our liquidity of $450 million, leaving us ample runway to pursue additional growth opportunities.

Summary:
We're thrilled to announce the acquisition of a 27 hotel portfolio from NewcrestImage, which is comprised of approximately 3,700 guest rooms located across 10 high-growth Sunbelt markets in Texas, Oklahoma City and New Orleans.
Our joint venture with GIC will acquire the assets for a total consideration of $822 million, and we will finance the investment with a new $410 million credit facility.
GIC's 49% equity interest will be a cash contribution totaling approximately $208 million, and our 51% controlling interest will come from a combination of common and preferred op units.
The utilization of common and preferred op units for our 51% equity interest will preserve nearly all of our liquidity of $450 million, leaving us ample runway to pursue additional growth opportunities.