Alterra Capital 8-K Results of Operations and Financial Condition

Exhibit 99.1

ALTERRA CAPITAL HOLDINGS LIMITED

Segment Re-presentation

(Unaudited)

This supplement is for information purposes only. It should be read in conjunction with documents filed by Alterra Capital Holdings Limited with the U.S. Securities and Exchange Commission pursuant to the Securities Exchange Act 1934.

Alterra Capital Holdings Limited

Investors:

Susan Spivak Bernstein, +1-212-898-6640

or

Media:

Kekst and Company

Peter Hill or Melissa Sheer, +1-212-521-4800

ALTERRA CAPITAL HOLDINGS LIMITED

Effective July 1, 2012 Alterra Capital Holdings Limited (“the Company”) redefined its reporting segments by combining the reinsurance and Latin America segments into a single reinsurance segment. The Latin America segment comprised reinsurance business written for clients in Latin America through the Company’s Rio de Janeiro, Bogotà and Buenos Aires offices. This business will now be combined with and reported as part of the reinsurance segment. Segment disclosures for comparative periods have been re-presented to reflect this change.

The Company monitors the performance of its underwriting operations in five segments: global insurance, U.S. insurance, reinsurance, Alterra at Lloyd’s and life and annuity reinsurance.

Global Insurance Segment - The Company’s global insurance segment offers property and casualty excess of loss insurance from its offices in Bermuda, Dublin and London primarily to Fortune 1000 companies. Principal lines of business include aviation, excess liability, professional liability and property.

U.S. Insurance Segment - The Company’s U.S. insurance segment offers property and casualty insurance coverage from offices in the United States primarily to Fortune 3000 companies. Principal lines of business include general liability, marine, professional liability and property.

Reinsurance Segment - The Company’s reinsurance segment offers property and casualty quota share and excess of loss reinsurance from its offices in Bermuda, Bogota, Buenos Aires, Dublin, London, Rio de Janeiro and the United States to insurance and reinsurance companies worldwide. Principal lines of business include agriculture, auto, aviation, credit/surety, general casualty, marine & energy, medical malpractice, professional liability, property, whole account and workers’ compensation.

Alterra at Lloyd’s Segment - The Company’s Alterra at Lloyd’s segment offers property and casualty quota share and excess of loss insurance and reinsurance from its offices in London, Dublin and Zurich primarily to medium to large sized international clients. Principal lines of business for this segment include accident & health, agriculture, aviation, financial institutions, international casualty, marine, professional liability and property.

Life and Annuity Reinsurance Segment - The Company’s life and annuity reinsurance segment operates out of Bermuda and offers reinsurance products focusing on blocks of life and annuity business, which take the form of co-insurance transactions whereby the risks are reinsured on the same basis as the original policies. The Company has determined not to write any new life and annuity contracts in the foreseeable future.

2

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–QUARTER ENDED MARCH 31, 2012 (Unaudited)

(Expressed in thousands of United States Dollars)

	Property & Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	66,771		$	104,282		$	343,694		$	146,143		$	660,890		$	440		$	—		$	661,330
Reinsurance premiums ceded		(43,251	)		(70,494	)		(72,109	)		(38,590	)		(224,444	)		(18	)		—			(224,462	)
Net premiums written	$	23,520		$	33,788		$	271,585		$	107,553		$	436,446		$	422		$	—		$	436,868
Earned premiums	$	94,103		$	96,241		$	214,184		$	72,899		$	477,427		$	440		$	—		$	477,867
Earned premiums ceded		(47,133	)		(40,456	)		(32,036	)		(20,049	)		(139,674	)		(18	)		—			(139,692	)
Net premiums earned		46,970			55,785			182,148			52,850			337,753			422			—			338,175
Net losses and loss expenses		(18,061	)		(37,564	)		(111,729	)		(38,675	)		(206,029	)		—			—			(206,029	)
Claims and policy benefits		—			—			—			—			—			(13,466	)		—			(13,466	)
Acquisition costs		(59	)		(7,696	)		(42,416	)		(9,434	)		(59,605	)		(119	)		—			(59,724	)
General and administrative expenses		(6,481	)		(12,257	)		(19,311	)		(9,095	)		(47,144	)		(34	)		—			(47,178	)
Other income (loss)		815			81			4,441			—			5,337			—			—			5,337
Underwriting income (loss)	$	23,184		$	(1,651	)	$	13,133		$	(4,354	)	$	30,312			n/a			—			n/a
Net investment income																	14,776			43,902			58,678
Net realized and unrealized gains on investments																				25,493			25,493
Net impairment losses recognized in earnings																				(5,369	)		(5,369	)
Corporate other income																				25			25
Interest expense																				(8,628	)		(8,628	)
Net foreign exchange gains																				32			32
Corporate general and administrative expenses																				(12,904	)		(12,904	)
Income before taxes																$	1,579		$	42,551		$	74,442
Loss ratio [a]		38.5	%		67.3	%		61.3	%		73.2	%		61.0	%
Acquisition cost ratio [b]		0.1	%		13.8	%		23.3	%		17.9	%		17.6	%
General and administrative expense ratio [c]		13.8	%		22.0	%		10.6	%		17.2	%		14.0	%
Combined ratio [d]		52.4	%		103.1	%		95.2	%		108.2	%		92.6	%

[a] The loss ratio is calculated by dividing net losses and loss expenses by net premiums earned for the property & casualty business.

[b] The acquisition cost ratio is calculated by dividing acquisition costs by net premiums earned for the property & casualty business.

[c] The general and administrative expense ratio is calculated by dividing general and administrative expenses by net premiums earned for the property & casualty business.

[d] The combined ratio is calculated by dividing the sum of net losses and loss expenses, acquisition costs and general and administrative expenses by net premiums earned for the property & casualty business.

Percentage totals may not add due to rounding.

n/a - Not applicable.

3

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–QUARTER ENDED JUNE 30, 2012 (Unaudited)

(Expressed in thousands of United States Dollars)

	Property & Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	125,276		$	112,186		$	256,333		$	72,008		$	565,803		$	1,054		$	—		$	566,857
Reinsurance premiums ceded		(53,224	)		(51,524	)		(57,908	)		(27,068	)		(189,724	)		(155	)		—			(189,879	)
Net premiums written	$	72,052		$	60,662		$	198,425		$	44,940		$	376,079		$	899		$	—		$	376,978
Earned premiums	$	92,803		$	100,300		$	233,352		$	69,330		$	495,785		$	1,054		$	—		$	496,839
Earned premiums ceded		(45,367	)		(44,490	)		(32,941	)		(23,108	)		(145,906	)		(155	)		—			(146,061	)
Net premiums earned		47,436			55,810			200,411			46,222			349,879			899			—			350,778
Net losses and loss expenses		(22,745	)		(37,333	)		(103,656	)		(33,030	)		(196,764	)		—			—			(196,764	)
Claims and policy benefits		—			—			—			—			—			(13,272	)		—			(13,272	)
Acquisition costs		(239	)		(6,169	)		(48,164	)		(7,443	)		(62,015	)		(156	)		—			(62,171	)
General and administrative expenses		(6,913	)		(12,215	)		(17,061	)		(7,856	)		(44,045	)		(119	)		—			(44,164	)
Other income (loss)		1			—			1,895			7			1,903			—			—			1,903
Underwriting income (loss)	$	17,540		$	93		$	33,425		$	(2,100	)	$	48,958			n/a			—			n/a
Net investment income																	13,466			41,263			54,729
Net realized and unrealized gains on investments																				13,481			13,481
Net impairment losses recognized in earnings																				(570	)		(570	)
Corporate other income																				25			25
Interest expense																				(9,635	)		(9,635	)
Net foreign exchange losses																				(25	)		(25	)
Corporate general and administrative expenses																				(14,613	)		(14,613	)
Income before taxes																$	818		$	29,926		$	79,702
Loss ratio		47.9	%		66.9	%		51.7	%		71.5	%		56.2	%
Acquisition cost ratio		0.5	%		11.1	%		24.0	%		16.1	%		17.7	%
General and administrative expense ratio		14.6	%		21.9	%		8.5	%		17.0	%		12.6	%
Combined ratio		63.0	%		99.8	%		84.3	%		104.6	%		86.6	%

4

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–QUARTER ENDED MARCH 31, 2011 (Unaudited)

(Expressed in thousands of U.S. Dollars)

	Property and Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	63,895		$	77,765		$	377,863		$	107,890		$	627,413		$	435		$	—		$	627,848
Reinsurance premiums ceded		(38,524	)		(38,317	)		(37,317	)		(23,179	)		(137,337	)		(20	)		—			(137,357	)
Net premiums written	$	25,371		$	39,448		$	340,546		$	84,711		$	490,076		$	415		$	—		$	490,491
Earned premiums	$	90,651		$	81,470		$	253,542		$	63,164		$	488,827		$	435		$	—		$	489,262
Earned premiums ceded		(40,779	)		(27,801	)		(20,195	)		(20,580	)		(109,355	)		(20	)		—			(109,375	)
Net premiums earned		49,872			53,669			233,347			42,584			379,472			415			—			379,887
Net losses and loss expenses		(31,624	)		(34,415	)		(189,924	)		(48,443	)		(304,406	)		—			—			(304,406	)
Claims and policy benefits		—			—			—			—			—			(14,710	)		—			(14,710	)
Acquisition costs		(264	)		(7,986	)		(49,547	)		(12,652	)		(70,449	)		(159	)		—			(70,608	)
General and administrative expenses		(7,952	)		(11,270	)		(24,728	)		(8,253	)		(52,203	)		(177	)		—			(52,380	)
Other income (loss)		729			83			—			215			1,027			—			—			1,027
Underwriting income (loss)		10,761			81			(30,852	)		(26,549	)		(46,559	)		n/a			—			n/a
Net investment income																	12,343			45,423			57,766
Net realized and unrealized gains (losses) on investments																	2,807			(21,625	)		(18,818	)
Net impairment losses recognized in earnings																				(1,029	)		(1,029	)
Corporate other income																				288			288
Interest expense																				(8,459	)		(8,459	)
Net foreign exchange gains																				878			878
Corporate general and administrative expenses																				(18,823	)		(18,823	)
Income (loss) before taxes																$	519		$	(3,347	)	$	(49,387	)
Loss ratio		63.4	%		64.1	%		81.4	%		113.8	%		80.2	%
Acquisition cost ratio		0.5	%		14.9	%		21.2	%		29.7	%		18.6	%
General and administrative expense ratio		15.9	%		21.0	%		10.6	%		19.4	%		13.8	%
Combined ratio		79.9	%		100.0	%		113.2	%		162.8	%		112.5	%

5

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–QUARTER ENDED JUNE 30, 2011 (Unaudited)

(Expressed in thousands of U.S. Dollars)

	Property and Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	130,909		$	109,794		$	249,846		$	72,428		$	562,977		$	930		$	—		$	563,907
Reinsurance premiums ceded		(55,133	)		(28,227	)		(28,247	)		(24,918	)		(136,525	)		(101	)		—			(136,626	)
Net premiums written	$	75,776		$	81,567		$	221,599		$	47,510		$	426,452		$	829		$	—		$	427,281
Earned premiums	$	88,892		$	82,244		$	212,825		$	58,117		$	442,078		$	930		$	—		$	443,008
Earned premiums ceded		(43,286	)		(23,835	)		(12,305	)		(14,540	)		(93,966	)		(101	)		—			(94,067	)
Net premiums earned		45,606			58,409			200,520			43,577			348,112			829			—			348,941
Net losses and loss expenses		(23,689	)		(38,012	)		(128,360	)		(21,072	)		(211,133	)		—			—			(211,133	)
Claims and policy benefits		—			—			��			—			—			(15,570	)		—			(15,570	)
Acquisition costs		1,117			(10,400	)		(45,329	)		(9,946	)		(64,558	)		(122	)		—			(64,680	)
General and administrative expenses		(6,774	)		(11,374	)		(24,700	)		(7,773	)		(50,621	)		(259	)		—			(50,880	)
Other income (loss)		85			54			548			165			852			(23	)		—			829
Underwriting income (loss)		16,345			(1,323	)		2,679			4,951			22,652			n/a			—			n/a
Net investment income																	12,545			47,120			59,665
Net realized and unrealized losses on investments																	(1,299	)		(4,475	)		(5,774	)
Net impairment losses recognized in earnings																				(353	)		(353	)
Corporate other income																				(238	)		(238	)
Interest expense																				(10,630	)		(10,630	)
Net foreign exchange losses																				(3,090	)		(3,090	)
Corporate general and administrative expenses																				(18,779	)		(18,779	)
(Loss) income before taxes																$	(3,899	)	$	9,555		$	28,308
Loss ratio		51.9	%		65.1	%		64.0	%		48.4	%		60.7	%
Acquisition cost ratio		(2.4	%)		17.8	%		22.6	%		22.8	%		18.5	%
General and administrative expense ratio		14.9	%		19.5	%		12.3	%		17.8	%		14.5	%
Combined ratio		64.3	%		102.4	%		98.9	%		89.0	%		93.7	%

6

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–QUARTER ENDED SEPTEMBER 30, 2011 (Unaudited)

(Expressed in thousands of U.S. Dollars)

	Property and Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	73,297		$	84,858		$	182,535		$	44,816		$	385,506		$	822		$	—		$	386,328
Reinsurance premiums ceded		(37,625	)		(30,579	)		(15,874	)		(6,723	)		(90,801	)		(90	)		—			(90,891	)
Net premiums written	$	35,672		$	54,279		$	166,661		$	38,093		$	294,705		$	732		$	—		$	295,437
Earned premiums	$	93,467		$	83,279		$	224,829		$	50,534		$	452,109		$	822		$	—		$	452,931
Earned premiums ceded		(48,456	)		(28,004	)		(18,489	)		(10,850	)		(105,799	)		(90	)		—			(105,889	)
Net premiums earned		45,011			55,275			206,340			39,684			346,310			732			—			347,042
Net losses and loss expenses		(21,288	)		(36,002	)		(116,769	)		(24,462	)		(198,521	)		—			—			(198,521	)
Claims and policy benefits		—			—			—			—			—			(14,538	)		—			(14,538	)
Acquisition costs		748			(9,669	)		(46,138	)		(6,230	)		(61,289	)		(145	)		—			(61,434	)
General and administrative expenses		(6,699	)		(10,228	)		(18,901	)		(8,007	)		(43,835	)		(145	)		—			(43,980	)
Other income (loss)		—			58			777			(27	)		808			(8	)		—			800
Underwriting income (loss)		17,772			(566	)		25,309			958			43,473			n/a			—			n/a
Net investment income																	12,131			48,204			60,335
Net realized and unrealized losses on investments																	(6,407	)		(1,565	)		(7,972	)
Net impairment losses recognized in earnings																				(861	)		(861	)
Corporate other income																				673			673
Interest expense																				(11,303	)		(11,303	)
Net foreign exchange gains																				147			147
Corporate general and administrative expenses																				(17,575	)		(17,575	)
(Loss) income before taxes																$	(8,380	)	$	17,720		$	52,813
Loss ratio		47.3	%		65.1	%		56.6	%		61.6	%		57.3	%
Acquisition cost ratio		(1.7	%)		17.5	%		22.4	%		15.7	%		17.7	%
General and administrative expense ratio		14.9	%		18.5	%		9.2	%		20.2	%		12.7	%
Combined ratio		60.5	%		101.1	%		88.1	%		97.5	%		87.7	%

7

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–QUARTER ENDED DECEMBER 31, 2011 (Unaudited)

(Expressed in thousands of U.S. Dollars)

	Property and Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	97,660		$	102,279		$	96,942		$	27,933		$	324,814		$	1,169		$	—		$	325,983
Reinsurance premiums ceded		(50,172	)		(45,443	)		(2,546	)		(8,888	)		(107,049	)		(154	)		—			(107,203	)
Net premiums written	$	47,488		$	56,836		$	94,396		$	19,045		$	217,765		$	1,015		$	—		$	218,780
Earned premiums	$	91,077		$	90,048		$	225,492		$	52,850		$	459,467		$	1,169		$	—		$	460,636
Earned premiums ceded		(42,827	)		(34,078	)		(19,521	)		(14,952	)		(111,378	)		(154	)		—			(111,532	)
Net premiums earned		48,250			55,970			205,971			37,898			348,089			1,015			—			349,104
Net losses and loss expenses		(15,152	)		(45,129	)		(106,906	)		(64,346	)		(231,533	)		—			—			(231,533	)
Claims and policy benefits		—			—			—			—			—			(14,564	)		—			(14,564	)
Acquisition costs		(1,084	)		(8,349	)		(46,839	)		(7,977	)		(64,249	)		(131	)		—			(64,380	)
General and administrative expenses		(6,952	)		(12,299	)		(16,690	)		(7,271	)		(43,212	)		(67	)		—			(43,279	)
Other income (loss)		(128	)		84			(100	)		851			707			413			—			1,120
Underwriting income (loss)		24,934			(9,723	)		35,436			(40,845	)		9,802			n/a			—			n/a
Net investment income																	11,515			45,565			57,080
Net realized and unrealized losses on investments																	(5,509	)		(266	)		(5,775	)
Net impairment losses recognized in earnings																				(702	)		(702	)
Corporate other income																				897			897
Interest expense																				(13,296	)		(13,296	)
Net foreign exchange gains																				753			753
Corporate general and administrative expenses																				(11,378	)		(11,378	)
(Loss) income before taxes																$	(7,328	)	$	21,573		$	24,047
Loss ratio		31.4	%		80.6	%		51.9	%		169.8	%		66.5	%
Acquisition cost ratio		2.2	%		14.9	%		22.7	%		21.0	%		18.5	%
General and administrative expense ratio		14.4	%		22.0	%		8.1	%		19.2	%		12.4	%
Combined ratio		48.1	%		117.5	%		82.7	%		210.0	%		97.4	%

8

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–YEAR ENDED DECEMBER 31, 2011 (Unaudited)

(Expressed in thousands of U.S. Dollars)

	Property and Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	365,761		$	374,696		$	907,186		$	253,067		$	1,900,710		$	3,356		$	—		$	1,904,066
Reinsurance premiums ceded		(181,454	)		(142,566	)		(83,984	)		(63,708	)		(471,712	)		(365	)		—			(472,077	)
Net premiums written	$	184,307		$	232,130		$	823,202		$	189,359		$	1,428,998		$	2,991		$	—		$	1,431,989
Earned premiums	$	364,087		$	337,041		$	916,688		$	224,665		$	1,842,481		$	3,356		$	—		$	1,845,837
Earned premiums ceded		(175,348	)		(113,718	)		(70,510	)		(60,922	)		(420,498	)		(365	)		—			(420,863	)
Net premiums earned		188,739			223,323			846,178			163,743			1,421,983			2,991			—			1,424,974
Net losses and loss expenses		(91,753	)		(153,558	)		(541,959	)		(158,323	)		(945,593	)		—			—			(945,593	)
Claims and policy benefits		—			—			—			—			—			(59,382	)		—			(59,382	)
Acquisition costs		517			(36,404	)		(187,853	)		(36,805	)		(260,545	)		(557	)		—			(261,102	)
General and administrative expenses		(28,377	)		(45,171	)		(85,019	)		(31,304	)		(189,871	)		(648	)		—			(190,519	)
Other income (loss)		686			279			1,225			1,204			3,394			382			—			3,776
Underwriting income (loss)		69,812			(11,531	)		32,572			(61,485	)		29,368			n/a			—			n/a
Net investment income																	48,534			186,312			234,846
Net realized and unrealized losses on investments																	(10,408	)		(27,931	)		(38,339	)
Net impairment losses recognized in earnings																				(2,945	)		(2,945	)
Corporate other income																				1,620			1,620
Interest expense																				(43,688	)		(43,688	)
Net foreign exchange losses																				(1,312	)		(1,312	)
Corporate general and administrative expenses																				(66,555	)		(66,555	)
(Loss) income before taxes																$	(19,088	)	$	45,501		$	55,781
Loss ratio		48.6	%		68.8	%		64.0	%		96.7	%		66.5	%
Acquisition cost ratio		(0.3	%)		16.3	%		22.2	%		22.5	%		18.3	%
General and administrative expense ratio		15.0	%		20.2	%		10.0	%		19.1	%		13.4	%
Combined ratio		63.4	%		105.3	%		96.3	%		138.3	%		98.2	%

9

ALTERRA CAPITAL HOLDINGS LIMITED

SCHEDULE OF SUPPLEMENTAL UNDERWRITING DATA–YEAR ENDED DECEMBER 31, 2010 (Unaudited)

(Expressed in thousands of U.S. Dollars)

	Property and Casualty
	Global Insurance			U.S. Insurance			Reinsurance (Re-presented)			Alterra at Lloyd’s			Total			Life & Annuity Reinsurance			Corporate			Consolidated
Gross premiums written	$	370,120		$	323,990		$	531,912		$	179,774		$	1,405,796		$	4,935		$	—		$	1,410,731
Reinsurance premiums ceded		(170,608	)		(98,576	)		(64,131	)		(37,448	)		(370,763	)		(400	)		—			(371,163	)
Net premiums written	$	199,512		$	225,414		$	467,781		$	142,326		$	1,035,033		$	4,535		$	—		$	1,039,568
Earned premiums	$	391,716		$	311,950		$	705,398		$	164,648		$	1,573,712		$	4,935		$	—		$	1,578,647
Earned premiums ceded		(173,123	)		(125,218	)		(71,627	)		(35,793	)		(405,761	)		(400	)		—			(406,161	)
Net premiums earned		218,593			186,732			633,771			128,855			1,167,951			4,535			—			1,172,486
Net losses and loss expenses		(128,823	)		(118,337	)		(352,491	)		(55,190	)		(654,841	)		—			—			(654,841	)
Claims and policy benefits		—			—			—			—			—			(65,213	)		—			(65,213	)
Acquisition costs		(3,381	)		(28,444	)		(132,831	)		(22,447	)		(187,103	)		(361	)		—			(187,464	)
General and administrative expenses		(28,615	)		(36,015	)		(70,639	)		(23,965	)		(159,234	)		(2,964	)		—			(162,198	)
Other income (loss)		760			507			—			2,534			3,801			286			—			4,087
Underwriting income		58,534			4,443			77,810			29,787			170,574			n/a			—			n/a
Net investment income																	49,785			172,673			222,458
Net realized and unrealized gains on investments																	11,358			5,514			16,872
Net impairment losses recognized in earnings																				(2,645	)		(2,645	)
Corporate other income																				721			721
Interest expense																				(28,275	)		(28,275	)
Net foreign exchange gains																				115			115
Merger and acquisition expenses																				48,776			48,776
Corporate general and administrative expenses																				(58,388	)		(58,388	)
(Loss) income before taxes																$	(2,574	)	$	138,491		$	306,491
Loss ratio		58.9	%		63.4	%		55.6	%		42.8	%		56.1	%
Acquisition cost ratio		1.5	%		15.2	%		21.0	%		17.4	%		16.0	%
General and administrative expense ratio		13.1	%		19.3	%		11.1	%		18.6	%		13.6	%
Combined ratio		73.6	%		97.9	%		87.7	%		78.8	%		85.7	%

10

ALTERRA CAPITAL HOLDINGS LIMITED

REINSURANCE SEGMENT DATA (Unaudited) - RE-PRESENTED

(Expressed in thousands of U.S. Dollars)

	FOR THE QUARTERS ENDED																		FOR THE YEARS ENDED
	June 30, 2012			Mar. 31, 2012			Dec. 31, 2011			Sept. 30, 2011			June 30, 2011			Mar. 31, 2011			Dec. 31, 2011			Dec. 31, 2010
Gross premiums written	$	256,333		$	343,694		$	96,942		$	182,535		$	249,846		$	377,863		$	907,186		$	531,912
Reinsurance premiums ceded		(57,908	)		(72,109	)		(2,546	)		(15,874	)		(28,247	)		(37,317	)		(83,984	)		(64,131	)
Net premiums written	$	198,425		$	271,585		$	94,396		$	166,661		$	221,599		$	340,546		$	823,202		$	467,781
Earned premiums	$	233,352		$	214,184		$	225,492		$	224,829		$	212,825		$	253,542		$	916,688		$	705,398
Earned premiums ceded		(32,941	)		(32,036	)		(19,521	)		(18,489	)		(12,305	)		(20,195	)		(70,510	)		(71,627	)
Net premiums earned		200,411			182,148			205,971			206,340			200,520			233,347			846,178			633,771
Net losses and loss expenses		(103,656	)		(111,729	)		(106,906	)		(116,769	)		(128,360	)		(189,924	)		(541,959	)		(352,491	)
Acquisition costs		(48,164	)		(42,416	)		(46,839	)		(46,138	)		(45,329	)		(49,547	)		(187,853	)		(132,831	)
General and administrative expenses		(17,061	)		(19,311	)		(16,690	)		(18,901	)		(24,700	)		(24,728	)		(85,019	)		(70,639	)
Other income (loss)		1,895			4,441			(100	)		777			548			—			1,225			—
Underwriting income (loss)	$	33,425		$	13,133		$	35,436		$	25,309		$	2,679		$	(30,852	)	$	32,572		$	77,810
Loss ratio		51.7	%		61.3	%		51.9	%		56.6	%		64.0	%		81.4	%		64.0	%		55.6	%
Acquisition cost ratio		24.0	%		23.3	%		22.7	%		22.4	%		22.6	%		21.2	%		22.2	%		21.0	%
General and administrative expense ratio		8.5	%		10.6	%		8.1	%		9.2	%		12.3	%		10.6	%		10.0	%		11.1	%
Combined ratio		84.3	%		95.2	%		82.7	%		88.1	%		98.9	%		113.2	%		96.3	%		87.7	%

11

ALTERRA CAPITAL HOLDINGS LIMITED

SEGMENT GROSS PREMIUMS WRITTEN BY LINE OF BUSINESS (Unaudited)

(Expressed in thousands of United States Dollars)

			FOR THE QUARTERS ENDED																FOR THE YEARS ENDED
			June 30, 2012			Mar. 31, 2012		Dec. 31, 2011			Sept. 30, 2011			June 30, 2011			Mar. 31, 2011		Dec. 31, 2011		Dec. 31, 2010
Property & Casualty:
Global Insurance:
Aviation		S	$	3,954		$	1,302	$	20,410		$	6,736		$	3,814		$	1,416	$	32,376	$	39,888
Excess Liability		L		31,435			25,186		21,281			20,365			34,659			22,277		98,582		89,933
Professional Liability		L		59,407			24,466		40,360			30,590			62,402			24,529		157,881		177,199
Property		S		30,480			15,817		15,609			15,606			30,034			15,673		76,922		63,100
				125,276			66,771		97,660			73,297			130,909			63,895		365,761		370,120
U.S. Insurance:
General/ Excess Liability		L		23,683			34,667		31,618			24,925			25,118			22,993		104,654		104,777
Marine		S		28,634			25,201		23,806			22,189			25,389			17,109		88,493		67,454
Professional Liability		L		13,133			11,208		15,720			13,318			8,509			6,622		44,169		12,454
Property		S		46,736			33,206		31,135			24,426			50,778			31,041		137,380		139,305
				112,186			104,282		102,279			84,858			109,794			77,765		374,696		323,990
Reinsurance (Re-presented) [a]:
Agriculture		S		5,298			17,505		186			998			8,713			20,785		30,682		29,222
Auto		S		39,590			512		20,548			7,716			55,072			15,024		98,360		32,285
Aviation		S		5,820			5,525		337			14,670			80			904		15,991		31,292
Credit/ Surety		S		3,266			35,850		6,764			8,484			1,555			24,407		41,210		7,004
General Casualty		L		23,625			14,956		13,130			22,870			22,268			16,384		74,652		50,394
Marine & Energy		S		6,610			13,395		3,407			4,131			(619	)		17,093		24,012		16,381
Medical Malpractice		L		8,105			11,276		1,673			6,867			11,223			17,582		37,345		51,391
Other		S		549			4,437		(181	)		1,112			447			1,693		3,071		2,729
Professional Liability		L		37,246			59,458		20,270			39,877			39,462			59,684		159,293		110,388
Property		S		117,629			161,124		21,645			70,274			107,071			152,801		351,791		166,129
Whole Account		S/L		191			1,408		2,408			(1,946	)		268			35,070		35,800		3,871
Workers’ Compensation		L		8,404			18,248		6,755			7,482			4,306			16,436		34,979		30,826
				256,333			343,694		96,942			182,535			249,846			377,863		907,186		531,912
Alterra at Lloyd’s:
Accident & Health		S		8,250			17,432		5,646			9,523			8,380			13,544		37,093		30,921
Agriculture		S		613			20,370		—			—			—			—		—		—
Aviation		S		3,220			2,486		5,562			4,130			1,810			1,767		13,269		16,138
Financial Institutions		L		5,400			6,904		8,137			3,591			6,441			9,036		27,205		19,448
International Casualty		L		8,423			49,268		1,947			7,903			8,263			33,789		51,902		25,489
Marine		S		2,282			2,726		1,493			—			—			—		1,493		—
Professional Liability		L		6,108			5,428		1,868			440			10,466			7,922		20,696		19,591
Property		S		37,712			41,529		3,280			19,229			37,068			41,832		101,409		68,187
				72,008			146,143		27,933			44,816			72,428			107,890		253,067		179,774
Aggregate Property & Casualty			$	565,803		$	660,890	$	324,814		$	385,506		$	562,977		$	627,413	$	1,900,710	$	1,405,796
Life & Annuity:
Annuity	��		$	(353	)	$	353	$	770		$	449		$	271		$	336	$	1,826	$	1,135
Life				1,407			87		399			373			659			99		1,530		3,800
Aggregate Life & Annuity			$	1,054		$	440	$	1,169		$	822		$	930		$	435	$	3,356	$	4,935
Aggregate Property & Casualty and Life & Annuity			$	566,857		$	661,330	$	325,983		$	386,328		$	563,907		$	627,848	$	1,904,066	$	1,410,731
S = Short tail lines			$	340,739		$	399,121	$	160,851		$	208,251		$	329,726		$	372,624	$	1,071,452	$	711,971
L = Long tail lines				225,064			261,769		163,963			177,255			233,251			254,789		829,258		693,825
Aggregate Property & Casualty			$	565,803		$	660,890	$	324,814		$	385,506		$	562,977		$	627,413	$	1,900,710	$	1,405,796
Property [b]			$	232,557		$	251,676	$	71,669		$	129,535		$	224,951		$	241,347	$	667,502	$	436,721
Casualty [c]				224,969			261,065		162,759			178,228			233,117			237,254		811,358		691,890
Specialty [d]				108,277			148,149		90,386			77,743			104,909			148,812		421,850		277,185
Aggregate Property & Casualty			$	565,803		$	660,890	$	324,814		$	385,506		$	562,977		$	627,413	$	1,900,710	$	1,405,796

[a] Includes the results of HarborPoint from May 12, 2010.

[b] Property includes property lines of business.

[c] Casualty includes excess liability, financial institutions, general liability, general casualty, international casualty, medical malpractice, professional liability and workers’ compensation lines of business.

[d] Specialty includes accident & health, agriculture, auto, aviation, credit/surety, energy, marine, other and whole account lines of business.

12