Headlines in the past 90 days have been a testament to the value of resilient supply chains.
Starting with our proprietary metrics with our view of the market, space utilization is 84.5%, up 100 basis points from the last 90 days.
Lease proposals reached 93 million square feet in the first quarter, a new high watermark and are up 30%[Phonetic] from 2020 adjusted for the size of our portfolio.
Lease signings were 60 million square feet, our second highest quarter on record.
Much of this activity is in new leasing, and as a result, retention was 69% for the quarter as we're optimizing the credit and rents.
Given our high volume of lease signings, our portfolio -- operating portfolio was 96.4% leased at quarter end.
Our leasing mix continues to broaden with strong demand continuing from space sizes above 100,000 square feet and small spaces demand is improving.
E-commerce demand remains elevated, representing 25% of new lease signings in the first quarter.
In the U.S., we now expect net absorption of 300 million square feet in 2021, which would be the highest in history.
This strong demand is being masked by supply, and we expect 300 million square feet of deliveries this year.
Vacancies are below 2% in many of our top markets such as Southern California, Toronto, Germany's main markets and Tokyo.
Houston, Madrid, Poland and West China, which taken together account for just over 5% of our NOI.
In the U.S., we expect replacement cost to increase 20% to 25% over the two-year period through 2021, the fastest rate ever.
For example, the team has procured steel for 5.2 million square feet of starts at pricing roughly 5% below market and providing us with the 10-week to 20-week schedule advantage.
Rent growth for the quarter, which was up 2.4% in the U.S., outperformed our expectations.
We are raising our 2021 rent forecast to 6.5% in the U.S. and 6% globally.
Our in-place to market rent spread now stands at 13.6%, up 80 basis points sequentially.
This represents future annual incremental organic NOI growth potential of more than $600 million.
Turning to valuations, logistics assets values are up a record 7.5% over the last two quarters.
Applying the valuation uplift to our $148 billion owned and managed portfolio, we estimate that the value of our real estate rose by more than $10 billion over the past two quarters.
For the quarter, core FFO was $0.97 per share, which includes net promote expense of $0.01.
Net effective rent change on rollover was 27%, led by the U.S. at 32%.
Occupancy at quarter end was 95.6%, down 60 basis points sequentially, in line with the normal first quarter seasonality.
Our share of cash same-store NOI growth was 4.5%, driven by the U.S. at 4.8%.
For strategic capital, our team raised $1.4 billion in the first quarter as investor demand remains robust.
Equity cues for our open-ended vehicles are at an all-time high, at more than $3 billion at quarter-end.
Looking at the balance sheet, we continue to maintain excellent financial strength with liquidity and combined leverage capacity between Prologis and our open-ended vehicles now totaling $14 billion.
We were able to get in front of the recent increase in interest rates and issued $3.5 billion of debt with a weighted average rate of 96 basis points and a term of 11 years.
This activity included the issuance of a 10-year U.S. dollar bond with the spread of 55 basis points, the lowest 10-year REIT bond spread ever and the completion of our 15th green bond offering.
Subsequent to quarter end, we closed on a green revolving credit facility, adding $500 million more capacity to our already exceptionally strong liquidity position.
We are increasing our cash same-store NOI growth midpoint by 75 basis points and narrowing the range to 4.5% to 5%.
We now expect bad debt expense to be in line with our historical average at approximately 20 basis points in gross revenues, down from our prior guidance midpoint of 30 basis points.
We're increasing our average occupancy midpoint for our operating portfolio by 50 basis points to 96.5%.
Strategic capital revenue, excluding promotes, will now range between $450 million and $460 million, up $12.5 million at the midpoint.
We are increasing development starts by $400 million, and now expect a midpoint of $2.9 billion.
Build-to-suits will comprise more than 40% of the volume.
Our land portfolio today comprised of land auctions and covered land place supports approximately $17 billion of future development.
We're increasing the midpoint for dispositions and contributions by $800 million in total.
Consistent with the rise in asset value and higher contributions, we're increasing realized development gains by $200 million with a new midpoint of $750 million.
Net deployment uses are now expected to be $50 million with leverage remaining effectively flat in 2021.
Putting this all together, we're increasing our core FFO midpoint by $0.06 and narrowing the range to $3.96 per share to $4.02 per share.
Core FFO, excluding promotes, will range between $3.98 per share and $4.04 per share, representing year-over-year growth at the midpoint of 12%.
Our efforts over the past 10 years to reposition the portfolio and balance sheet have set us up to outperform in 2021 and beyond.

Summary:
For the quarter, core FFO was $0.97 per share, which includes net promote expense of $0.01.
Our share of cash same-store NOI growth was 4.5%, driven by the U.S. at 4.8%.
We are increasing our cash same-store NOI growth midpoint by 75 basis points and narrowing the range to 4.5% to 5%.
Putting this all together, we're increasing our core FFO midpoint by $0.06 and narrowing the range to $3.96 per share to $4.02 per share.