Securities sold under agreements to repurchase generally mature within one to seven days from the transaction date. Securities underlying the repurchase agreements remain under the control of the Company.

Information concerning the Company’s securities sold under agreements to repurchase as of December 31, 2018 and 2017 is summarized as follows:

	December 31,
(In thousands)	2018			2017
Balance at period end	$	1,106		$	1,026
Average balance during the period		1,630			3,371
Average interest rate during the period		0.25	%		0.25	%
Maximum month-end balance during the period	$	2,384		$	6,286

Repurchase agreements are treated as collateralized financing obligations and are reflected as a liability in the consolidated balance sheets. The carrying value of investment securities collateralizing repurchase agreements was $3.3 million and $7.5 million and December 31, 2018 and 2017, respectively.

In June 2014, the Company and the Bank completed an unregistered $245 million multi-tranche debt transaction and in March 2015, the Company completed an unregistered $50 million debt transaction. These transactions enhanced our liquidity and regulatory capital levels to support balance sheet growth. Details of the debt transactions are as follows:

(In thousands)	2018			2017
Cadence Bancorporation:
4.875% senior notes, due June 28, 2019	$	145,000		$	145,000
5.375% senior notes, due June 28, 2021		50,000			50,000
7.250% subordinated notes, due June 28, 2029, callable in 2024		35,000			35,000
6.500% subordinated notes, due March 2025, callable in 2020		40,000			40,000
Total — Cadence Bancorporation		270,000			270,000
Cadence Bank:
6.250% subordinated notes, due June 28, 2029, callable in 2024		25,000			25,000
Debt issue cost and unamortized premium		(1,211	)		(1,606	)
Purchased 4.875% senior notes, due June 28, 2019		(10,078	)		(10,078	)
Total	$	283,711		$	283,316

The senior transactions were structured with 4 and 7 year maturities to provide holding company liquidity and to stagger the Company’s debt maturity profile. The $35 million and $25 million subordinated debt transactions were structured with a 15 year maturity, 10 year call options, and fixed-to-floating interest rates in order to maximize regulatory capital treatment. These subordinated debt structures were designed to achieve full Tier 2 capital treatment for 10 years. The $40 million subordinated debt transaction has a 5 year call option.

The Company’s senior notes are unsecured, unsubordinated obligations and are equal in right of payment to all of the Company’s other unsecured debt. The Company’s subordinated notes are unsecured obligations and will be subordinated in right of payment to all of the Company’s senior indebtedness and general creditors and to depositors at the Bank. The Company’s senior notes and subordinated notes are not guaranteed by any subsidiary of the Company, including the Bank.

The Bank’s subordinated notes are unsecured obligations and are subordinated in right of payment to all of the Bank’s senior indebtedness and general creditors and to depositors of the Bank. The Bank’s subordinated notes are not guaranteed by the Company or any subsidiary of the Bank.

Payment of principal on the Company’s and Bank’s subordinated notes may be accelerated by holders of such subordinated notes only in the case of certain insolvency events. There is no right of acceleration under the subordinated notes in the case of default. The Company and/or the Bank may be required to obtain the prior written approval of the Federal Reserve, and, in the case of the Bank, the OCC, before it may repay the subordinated notes issued thereby upon acceleration or otherwise.

In conjunction with the Company’s acquisition of Cadence Financial Corporation and Encore Bank, N.A., the junior subordinated debentures were marked to fair value as of their respective acquisition dates. The related mark is being amortized over the remaining term of the junior subordinated debentures. The following is a list of junior subordinated debt:

	December 31,
(In thousands)	2018			2017
Junior subordinated debentures, 3 month LIBOR plus 2.85%, due 2033	$	30,000		$	30,000
Junior subordinated debentures, 3 month LIBOR plus 2.95%, due 2033		5,155			5,155
Junior subordinated debentures, 3 month LIBOR plus 1.75%, due 2037		15,464			15,464
Total par value		50,619			50,619
Purchase accounting adjustment, net of amortization		(13,666	)		(14,147	)
Total junior subordinated debentures	$	36,953		$	36,472

FHLB advances were $150 million at December 31, 2018 and 2017. Advances are collateralized by $1.6 billion of commercial and residential real estate loans pledged under a blanket lien arrangement as of December 31, 2018.

As of December 31, 2018 and 2017, the FHLB has issued for the benefit of the Bank irrevocable letters of credit totaling $590.0 million and $386.5 million, respectively. Included in the FHLB letters of credit is a $35 million irrevocable letter of credit in favor of the State of Alabama SAFE Program to secure certain deposits of the State of Alabama. This letter of credit expires September 28, 2020 upon 45 days’ prior notice of non-renewal; otherwise it automatically extends for a successive one-year term. The Bank also has a $555 million in irrevocable letters of credit to secure a large public fund treasury management deposit. Of this amount, $205 million expired in January 2019, while $350 million will expire May 26, 2021 upon 45 days’ prior notice of non-renewal; otherwise it automatically extends for a successive one-year term.

There were no borrowings from the FRB discount window as of December 31, 2018 and 2017. Any borrowings from the FRB will be collateralized by $740.3 million in commercial loans pledged under a borrower-in-custody arrangement.