In the second quarter, lease signings were 64 million square feet and lease proposals were 84 million square feet, both remained above average and were driven by new and development leasing.
Currently, the greatest demand is for spaces above 100,000 square feet.
We signed 518 leases totaling 18 million square feet in the quarter, the highest volume in this segment in three years.
For customer segments, e-commerce continues to lead the way, representing 30% of new lease signings in the second quarter.
While Amazon remains steady at 6% of total new leasing, we have seen many mortgage commerce players come to the table.
For example, we signed 168 new e-commerce leases in the first half of 2021 versus 53 in the first half of last year.
Containerized imports are up 33% through May versus pre-pandemic levels as retailers replenish their supply chains.
While inventories have risen 3% from their trough, they have struggled to grow this year as retail sales are up 19% from pre-pandemic levels.
We see the current low level of inventories in our space utilization, which at 84.3% is below the long-term average of 85%.
Putting together recent outperformance and ongoing momentum, we are raising our 2021 U.S. forecast for net absorption by 20% to 360 million square feet and deliveries by 8% to 325 million square feet.
Looking forward, we foresee continued supply balanced by demand with historic low vacancy of 4.5% carrying into 2022.
Our operating portfolio lease percentage rose by 80 basis points to 97.2% at quarter end.
Customers continue to compete for space and are making decisions faster with lease gestation in the quarter of just 44 days.
Accelerating demand in the quarter combined with ultra-low vacancies translated to a very strong rent growth of 4.1% in our U.S. markets, exceeding our expectations.
As a result, we are raising our 2021 rent forecast an all time high of 10.3% for the U.S., up approximately 40 basis points from our prior estimate and 8% globally, which is up 300 basis points.
Our in-place to market rent spread is now the widest in our history at 16.9%, up 330 basis points sequentially.
This represents future gas in the tank of nearly $700 million in NOI or $0.90 per share.
Our assets have strongest quarterly uplift in our history, rising 8% in the second quarter alone with the U.S. up more than 10% and Europe up 5.6%.
Core FFO was $1.01 per share with net promote earnings effectively zero, rent change on rollover was 32%.
Occupancy at quarter end was 96.8%, up 110 basis points sequentially.
Cash same-store NOI growth accelerated by 5.8%, up 290 basis points year-over-year.
We tapped into favorable market conditions and disposed off $880 million of non-strategic assets across our portfolio.
In addition, just last week, we completed the sale of a $920 million owned and managed portfolio including all of the non-strategic IPT assets.
It's worth noting that to date we have sold $2 billion of non-strategic assets from our IPT and LPT acquisitions by pricing more than 23% above underwriting.
Our team raised almost $600 million in the second quarter.
Equity cues from our open-ended vehicles [Indecipherable] $3.3 billion at quarter end, hitting another all-time high.
For the balance sheet, we continue to maintain excellent financial strength with liquidity and combined leverage capacity between Prologis and our open-ended vehicles totaling $14 billion.
We're increasing our cash same-store NOI growth midpoint by 75 basis points to now range between 5.25% and 5.75%.
We expect bad debt expense to be approximately 10 basis points of gross revenues, down from our prior guidance midpoint of 20 basis points and well below our historical average.
We are increasing the midpoint for strategic capital revenue, excluding promotes, to $470 million, up $15 million from prior guidance.
We now expect net promote income of $0.02 for this year, an increase of $0.04 from our prior guidance.
We're also increasing development starts by $300 million and now expect a midpoint of $3.2 billion.
Build-to-suits will comprise more than 40% of development volume.
Our owned and managed land portfolios compose of land, options and covered land place supports $18 billion of future development over the next several years.
We are also increasing the midpoint for dispositions and contributions by $650 million in total.
This increase will have roughly a $0.02 drag on earnings this year given the timing to redeploy incremental proceeds.
We now expect to generate net deployment sources of $200 million at the midpoint with leverage remaining effectively flat in 2021.
Taking into assumption there is no account, we're increasing our core FFO midpoint by $0.07 and narrowing the range to $4.04 to $4.08 per share.
Core FFO excluding promotes will range between $4.02 and $4.06 per share, representing year-over-year growth at the midpoint of almost 13%.
We continue to maintain exceptional dividend coverage, and our 2021 guidance implies a payout ratio in the low-60% range and free cash flow after dividends of $1.3 billion.

Summary:
Core FFO was $1.01 per share with net promote earnings effectively zero, rent change on rollover was 32%.
Cash same-store NOI growth accelerated by 5.8%, up 290 basis points year-over-year.
Taking into assumption there is no account, we're increasing our core FFO midpoint by $0.07 and narrowing the range to $4.04 to $4.08 per share.
Core FFO excluding promotes will range between $4.02 and $4.06 per share, representing year-over-year growth at the midpoint of almost 13%.