(1)	Weighted average effective interest rate as of March 31, 2020.

(2)	Includes variable rate mortgages payable with interest rates fixed by interest rate swap agreements.

As of March 31, 2020 and December 31, 2019, the net carrying value of real estate collateralizing our mortgages payable totaled $1.6 billion and $1.4 billion. Our mortgages payable contain covenants that limit our ability to incur additional indebtedness on these properties and, in certain circumstances, require lender approval of tenant leases and/or yield maintenance upon repayment prior to maturity. Certain of our mortgages payable are recourse to us. See Note 17 for additional information.

During the three months ended March 31, 2020, we entered into a mortgage loan with a principal balance of $175.0 million collateralized by 4747 Bethesda Avenue. In April 2020, we refinanced the mortgage loan collateralized by RTC-West, increasing the principal balance to $117.3 million from $97.1 million. During the three months ended March 31, 2020, we repaid mortgages payable with an aggregate principal balance of $2.2 million.

As of March 31, 2020 and December 31, 2019, we had various interest rate swap and cap agreements on certain of our mortgages payable with an aggregate notional value of $1.0 billion and $867.6 million. See Note 15 for additional information.

Credit Facility

As of March 31, 2020, our $1.4 billion credit facility consisted of a $1.0 billion revolving credit facility maturing in January 2025, a delayed draw $200.0 million unsecured term loan ("Tranche A-1 Term Loan") maturing in January 2023, and a delayed draw $200.0 million unsecured term loan ("Tranche A-2 Term Loan") maturing in July 2024. As of December 31, 2019, we had an outstanding balance of $200.0 million under the revolving credit facility, which was repaid in February 2020. In March 2020, we drew $200.0 million under the revolving credit facility. In April 2020, we drew an additional $300.0 million under the revolving credit facility and the remaining $100.0 million under our Tranche A-1 Term Loan.

As of March 31, 2020 and December 31, 2019, we had interest rate swaps with an aggregate notional value of $300.0 million and $237.6 million. The interest rate swaps effectively convert the variable interest rate applicable to our Tranche A-1 and A-2 Term Loans to a fixed interest rate. The interest rate swaps applicable to our Tranche A-1 and A-2 Term Loans mature in January 2023 and July 2024 and provide a weighted average base interest rate under the Tranche A-1 and A-2 Term Loans of 2.12% and 1.34% per annum as of March 31, 2020. As of March 31, 2020, we had a forward-starting swap with an effective date of July 18, 2020 and a notional value of $100.0 million, which will effectively convert the variable interest rate applicable to the April 2020 draw of $100.0 million under our Tranche A-1 Loan to a fixed interest rate upon the effective date of the swap.

The following is a summary of amounts outstanding under the credit facility:


	Effective
	Interest Rate ⁽¹⁾	March 31, 2020		December 31, 2019
		(In thousands)
Revolving credit facility ^{(2) (3) (4)}	2.04%	$	200,000	$	200,000

Tranche A-1 Term Loan ⁽⁵⁾	3.32%	$	100,000	$	100,000
Tranche A-2 Term Loan ⁽⁶⁾	2.49%		200,000		200,000
Unsecured term loans			300,000		300,000
Unamortized deferred financing costs, net			(2,534)		(2,705)
Unsecured term loans, net		$	297,466	$	297,295

(1)	Effective interest rate as of March 31, 2020.

(2)	As of both March 31, 2020 and December 31, 2019, letters of credit with an aggregate face amount of $1.5 million were outstanding under our revolving credit facility.

(3)	As of March 31, 2020 and December 31, 2019, net deferred financing costs related to our revolving credit facility totaling $7.9 million and $3.1 million were included in "Other assets, net."

(4)	The interest rate for the revolving credit facility excludes a 0.15% facility fee. In April 2020, we drew an additional $300.0 million under the revolving credit facility.

(5)	As of March 31, 2020 and December 31, 2019, the outstanding balance was fixed by interest rate swap agreements. In April 2020, we drew $100.0 million under the Tranche A-1 Term Loan.

(6)	As of March 31, 2020 and December 31, 2019, the outstanding balance was fixed by interest rate swap agreements with a notional value of $200.0 million and $137.6 million.