balance sheet and lower our overall cost of capital. We raised close to $675 million in new equity and debt, redeemed approximately $700 million in more expensive debt and preferred stock, and expanded our unsecured credit facilities to $900 million.
And finally, throughout the year, we continue to build our enterprise capabilities. We added key personnel to our already strong management team, deepening our expertise in the pursuit and execution of our current and future development portfolio and including our projects in the life science area.
Now, let me review the fourth quarter, which was led by strong leasing activity. We signed leases totaling more than 1.4 million square feet in the quarter, putting a meaningful dent in expirations occurring over the next 12 months and securing a top-quality tenant for the entire office portion of The Exchange at 16th.
In our stabilized portfolio, we signed new or renewing leases on 678,000 square feet. Rents were 15% higher on a GAAP basis and excluding one-year lease extension in Los Angeles, 18.3% higher on a cash basis. The largest executed lease in the stabilized portfolio was a 10-year 207,000 square foot transaction with Okta for all of Delta Dental's 188,000 square feet, plus an additional 19,000 square feet at our 100 First Street office property in San Francisco's SOMA district.
This lease removes a key 2018 expiration, and was executed well before Delta Dental's move out at the end of May. Cash rents were up 27% on a GAAP basis. Our cash rents were up 27%, and GAAP rents were up 51%. In addition, Okta has a must-take on our additional 48,000 square feet in the building that will become available in 2020. Tyler will provide more color on occupancy in his section.
Moving to our development program. As we discussed on our last quarter's call, in October, we signed a 15-year lease with Dropbox for 100% of the office space at The Exchange, our four-building 750,000 square foot office and retail development project in San Francisco's Mission Bay neighborhood. It was the largest single Class A commercial transaction ever completed in this city.
The size in terms of this lease are indicative of the robust market demand for this type of creative, collaborative and sustainable workspace design. With The Exchange fully leased, we commenced construction in January on the first phase of Academy & Vine, which will follow Columbia Square as our second mixed-use project in Hollywood. The first phase of development includes the project's 306,000 square feet of office space, 24,000 square feet of retail and parking and site work for the overall project. The anticipated completion date is 2020, and total incremental spending for phase one is projected to be $190 million.
Hollywood continues to benefit from strong market fundamentals of low supply and strong demand. Market strength is not only being driven by growth in content creation from Apple, Netflix, Facebook, Amazon and others, which have all announced plans to invest billions, but also by small and