Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2024

Stockholders' Equity Note [Abstract]

Table of Actual Regulatory Capital Amounts and Ratios

The following table provides Trustmark’s and TNB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at September 30, 2024 and December 31, 2023 ($ in thousands):

	Actual
	Regulatory Capital					Minimum			To Be Well
	Amount		Ratio			Requirement			Capitalized
At September 30, 2024:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,694,769		11.30	%		7.00	%	n/a
Trustmark National Bank		1,800,019		12.00	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,754,769		11.70	%		8.50	%	n/a
Trustmark National Bank		1,800,019		12.00	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	2,057,073		13.71	%		10.50	%	n/a
Trustmark National Bank		1,978,676		13.19	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,754,769		9.65	%		4.00	%	n/a
Trustmark National Bank		1,800,019		9.90	%		4.00	%		5.00	%
At December 31, 2023:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,521,665		10.04	%		7.00	%	n/a
Trustmark National Bank		1,602,327		10.58	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,581,665		10.44	%		8.50	%	n/a
Trustmark National Bank		1,602,327		10.58	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,862,246		12.29	%		10.50	%	n/a
Trustmark National Bank		1,759,426		11.61	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,581,665		8.62	%		4.00	%	n/a
Trustmark National Bank		1,602,327		8.75	%		4.00	%		5.00	%

Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects

The following table presents the net change in the components of accumulated other comprehensive income (loss) and the related tax effects allocated to each component for the periods presented ($ in thousands).

	Three Months Ended September 30, 2024							Three Months Ended September 30, 2023
	Before Tax Amount		Tax (Expense) Benefit			Net of Tax Amount		Before Tax Amount			Tax (Expense) Benefit			Net of Tax Amount
Securities available for sale and transferred    securities:
Net unrealized holding gains (losses) arising    during the period	$	55,892	$	(13,973	)	$	41,919	$	(26,963	)	$	6,740		$	(20,223	)
Reclassification adjustment for net (gains) losses    realized in net income		—		—			—		—			—			—
Change in net unrealized holding loss on    securities transferred to held to maturity		3,688		(922	)		2,766		4,000			(1,000	)		3,000
Total securities available for sale    and transferred securities		59,580		(14,895	)		44,685		(22,963	)		5,740			(17,223	)
Pension and other postretirement benefit plans:
Reclassification adjustments for changes    realized in net income:
Net change in prior service costs		28		(7	)		21		28			(7	)		21
Recognized net loss due to lump sum    settlements		—		—			—		—			—			—
Change in net actuarial loss		84		(21	)		63		70			(18	)		52
Total pension and other postretirement    benefit plans		112		(28	)		84		98			(25	)		73
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective    cash flow hedge derivatives		18,826		(4,706	)		14,120		(11,338	)		2,834			(8,504	)
Reclassification adjustment for (gain) loss    realized in net income		4,831		(1,208	)		3,623		4,627			(1,157	)		3,470
Total cash flow hedge derivatives		23,657		(5,914	)		17,743		(6,711	)		1,677			(5,034	)
Total other comprehensive income (loss)	$	83,349	$	(20,837	)	$	62,512	$	(29,576	)	$	7,392		$	(22,184	)

	Nine Months Ended September 30, 2024									Nine Months Ended September 30, 2023
	Before Tax Amount			Tax (Expense) Benefit			Net of Tax Amount			Before Tax Amount			Tax (Expense) Benefit			Net of Tax Amount
Securities available for sale and transferred    securities:
Net unrealized holding gains (losses) arising    during the period	$	47,579		$	(11,895	)	$	35,684		$	(16,062	)	$	4,246		$	(11,816	)
Reclassification adjustment for net (gains) losses    realized in net income		182,792			(45,698	)		137,094			—			—			—
Change in net unrealized holding loss on    securities transferred to held to maturity		11,020			(2,755	)		8,265			11,799			(2,950	)		8,849
Total securities available for sale    and transferred securities		241,391			(60,348	)		181,043			(4,263	)		1,296			(2,967	)
Pension and other postretirement benefit plans:
Reclassification adjustments for changes    realized in net income:
Net change in prior service costs		83			(21	)		62			83			(21	)		62
Recognized net loss due to lump sum    settlements		(13	)		3			(10	)		25			(6	)		19
Change in net actuarial loss		263			(65	)		198			216			(54	)		162
Total pension and other postretirement    benefit plans		333			(83	)		250			324			(81	)		243
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective    cash flow hedge derivatives		(2,007	)		502			(1,505	)		(24,569	)		6,142			(18,427	)
Reclassification adjustment for (gain) loss    realized in net income		14,520			(3,630	)		10,890			11,555			(2,889	)		8,666
Total cash flow hedge derivatives		12,513			(3,128	)		9,385			(13,014	)		3,253			(9,761	)
Total other comprehensive income (loss)	$	254,237		$	(63,559	)	$	190,678		$	(16,953	)	$	4,468		$	(12,485	)

Summary of Changes in Balances of Accumulated Other Comprehensive Income (Loss)

The following table presents the changes in the balances of each component of accumulated other comprehensive income (loss) for the periods presented ($ in thousands). All amounts are presented net of tax.

	Securities Available for Sale and Transferred Securities			Defined Benefit Pension Items			Cash Flow Hedge Derivatives			Total
Balance at January 1, 2024	$	(204,670	)	$	(6,075	)	$	(8,978	)	$	(219,723	)
Other comprehensive income (loss) before reclassification		43,949			—			(1,505	)		42,444
Amounts reclassified from accumulated other    comprehensive income (loss)		137,094			250			10,890			148,234
Net other comprehensive income (loss)		181,043			250			9,385			190,678
Balance at September 30, 2024	$	(23,627	)	$	(5,825	)	$	407		$	(29,045	)
Balance at January 1, 2023	$	(254,442	)	$	(5,792	)	$	(15,169	)	$	(275,403	)
Other comprehensive income (loss) before reclassification		(2,967	)		—			(18,427	)		(21,394	)
Amounts reclassified from accumulated other    comprehensive income (loss)		—			243			8,666			8,909
Net other comprehensive income (loss)		(2,967	)		243			(9,761	)		(12,485	)
Balance at September 30, 2023	$	(257,409	)	$	(5,549	)	$	(24,930	)	$	(287,888	)