Those opportunities that are immediately in front of us, those that will cultivate over the next 18 to 24 months, and those that will materialize over the long term.
During the fourth quarter, KRG leased over 900,000 square feet at a very strong 12.9% blended cash spread on comparable new and renewal leases.
The blended spread on our fourth quarter comparable non-option renewals was 10.2%.
For the full year, KRG leased over 2.6 million square feet at blended cash spreads on a comparable deals of 10.7%.
If we include the active -- the activity from the legacy RPAI assets for all of 2021, we leased over 5.1 million square feet for the combined portfolio.
Based on this progress, our retail lease percentage stands at 93.4%, up 220 basis points over last year, and yet, we still have significant upside.
The portfolio has signed not-open NOI of approximately $33 million, which will primarily come online during the back half of 2022 and the first half of 2023.
The good news is that the $33 million of signed not-open NOI represents about half of the near-term leasing-related NOI opportunity.
For example, during the quarter, we entered into an agreement with Republic Airways to develop a new $200 million corporate campus on an outdated retail location owned by KRG in Carmel, Indiana.
Therefore, we sold a portion of the land to Republic for approximately $7 million and will serve as the master developer of their campus.
KRG will not only receive a sizable development fee but also a profit component, all the while putting 0 KRG capital at risk.
Having been in this business for over 30 years, having visited nearly every legacy RPAI asset, I can unequivocally tell you that the quality of our portfolio improved by virtue of the merger.
We have a sector-leading presence with over 60% of our ABR in these markets, 40% alone being in Texas and Florida.
For the fourth quarter, KRG generated $0.43 of FFO per share.
As compared to NAREIT, our as adjusted FFO results add back in the $76 million of merger-related costs and deduct the $400,000 of net prior period activity.
For the full year, KRG generated $1.50 of FFO per share, as compared to NAREIT, or as adjusted FFO adds back in the $87 million of merger-related costs and deducts the $3.7 million of prior period activities.
Our same-property growth for the fourth quarter and full year is 7.2% and 6.1%, respectively.
Absent the net contribution from prior-period activities, the fourth quarter and the full year same-property NOI growth is 6.8% and 4.3%, respectively.
Our net debt to EBITDA was 6x, down from 6.1 times last quarter.
Adding in $33 million of signed, but not-open, NOI from the combined portfolio, our net debt to EBITDA would be 5.6 times.
As John alluded to earlier, we are providing FFO as adjusted guidance of $1.69 to $1.75 per share.
The variance from NAREIT FFO is approximately $0.02, which represents our estimate of $4 million of nonrecurring merger-related costs.
Furthermore, the accounting adjustments related to the legacy RPAI below-market leases and above-market debt, contribute an incremental $0.06 of FFO per share to our 2022 guidance.
Additional assumptions at the midpoint include neutral impact from any transactional activity and bad debt of 1.5% of total revenues.
In order to avoid any confusion, we are assuming same-property NOI growth of 2% at the midpoint, excluding the net impact of prior period adjustments.
This estimated 2% same-property growth is primarily driven by occupancy gains and contractual rent bumps.
Last week, KRG declared a dividend of $0.20 per share for the first quarter.
This represents a 5% sequential increase and an 18% year-over-year increase.
I think another compelling comparison is to look at our original 2020 FFO guidance of $1.50 per share at the midpoint.
Like our peers, we gave this guidance before the pandemic set in and reflected KRG's run rate after selling over $0.5 billion of assets in connection with Project Focus.
Our 2022 per share guidance represents a 15% increase over our original 2020 per share guidance at the midpoint.
On a per-share basis, not only we return to pre-pandemic levels, but we tacked on another 15%.

Summary:
For the fourth quarter, KRG generated $0.43 of FFO per share.
As John alluded to earlier, we are providing FFO as adjusted guidance of $1.69 to $1.75 per share.