Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2025

Stockholders' Equity Note [Abstract]

Table of Actual Regulatory Capital Amounts and Ratios

The following table provides Trustmark’s and TB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at September 30, 2025 and December 31, 2024 ($ in thousands):

	Actual
	Regulatory Capital					Minimum			To Be Well
	Amount		Ratio			Requirement			Capitalized
At September 30, 2025:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,812,783		11.88	%		7.00	%	n/a
Trustmark Bank		1,888,425		12.37	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,872,783		12.27	%		8.50	%	n/a
Trustmark Bank		1,888,425		12.37	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	2,187,443		14.33	%		10.50	%	n/a
Trustmark Bank		2,079,189		13.62	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,872,783		10.26	%		4.00	%	n/a
Trustmark Bank		1,888,425		10.35	%		4.00	%		5.00	%
At December 31, 2024:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,729,672		11.54	%		7.00	%	n/a
Trustmark Bank		1,828,044		12.20	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,789,672		11.94	%		8.50	%	n/a
Trustmark Bank		1,828,044		12.20	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	2,094,874		13.97	%		10.50	%	n/a
Trustmark Bank		2,009,544		13.41	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,789,672		9.99	%		4.00	%	n/a
Trustmark Bank		1,828,044		10.21	%		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, 2025									Three Months Ended September 30, 2024
	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	$	9,714		$	(2,428	)	$	7,286		$	55,892	$	(13,973	)	$	41,919
Reclassification adjustment for net (gains) losses    realized in net income		—			—			—			—		—			—
Change in net unrealized holding loss on    securities transferred to held to maturity		3,422			(855	)		2,567			3,688		(922	)		2,766
Total securities available for sale    and transferred securities		13,136			(3,283	)		9,853			59,580		(14,895	)		44,685
Pension and other postretirement benefit plans:
Reclassification adjustments for changes    realized in net income:
Net change in prior service costs		4			(2	)		2			28		(7	)		21
Recognized net loss due to lump sum    settlements		(29	)		8			(21	)		—		—			—
Change in net actuarial loss		61			(15	)		46			84		(21	)		63
Total pension and other postretirement    benefit plans		36			(9	)		27			112		(28	)		84
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective    cash flow hedge derivatives		(822	)		205			(617	)		18,826		(4,706	)		14,120
Reclassification adjustment for (gain) loss    realized in net income		2,462			(616	)		1,846			4,831		(1,208	)		3,623
Total cash flow hedge derivatives		1,640			(411	)		1,229			23,657		(5,914	)		17,743
Total other comprehensive income (loss)	$	14,812		$	(3,703	)	$	11,109		$	83,349	$	(20,837	)	$	62,512

	Nine Months Ended September 30, 2025									Nine Months Ended September 30, 2024
	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	$	56,305		$	(14,076	)	$	42,229		$	47,579		$	(11,895	)	$	35,684
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		10,297			(2,574	)		7,723			11,020			(2,755	)		8,265
Total securities available for sale    and transferred securities		66,602			(16,650	)		49,952			241,391			(60,348	)		181,043
Pension and other postretirement benefit plans:
Reclassification adjustments for changes    realized in net income:
Net change in prior service costs		11			(3	)		8			83			(21	)		62
Recognized net loss due to lump sum    settlements		(79	)		20			(59	)		(13	)		3			(10	)
Change in net actuarial loss		193			(48	)		145			263			(65	)		198
Total pension and other postretirement    benefit plans		125			(31	)		94			333			(83	)		250
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective    cash flow hedge derivatives		11,155			(2,789	)		8,366			(2,007	)		502			(1,505	)
Reclassification adjustment for (gain) loss    realized in net income		7,823			(1,956	)		5,867			14,520			(3,630	)		10,890
Total cash flow hedge derivatives		18,978			(4,745	)		14,233			12,513			(3,128	)		9,385
Total other comprehensive income (loss)	$	85,705		$	(21,426	)	$	64,279		$	254,237		$	(63,559	)	$	190,678

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, 2025	$	(66,885	)	$	(4,721	)	$	(12,053	)	$	(83,659	)
Other comprehensive income (loss) before    reclassification		49,952			—			8,366			58,318
Amounts reclassified from accumulated other    comprehensive income (loss)		—			94			5,867			5,961
Net other comprehensive income (loss)		49,952			94			14,233			64,279
Balance at September 30, 2025	$	(16,933	)	$	(4,627	)	$	2,180		$	(19,380	)
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	)