Exhibit 99.10

PINNACLE WEST CAPITAL CORPORATION
NON-GAAP FINANCIAL MEASURE RECONCILIATION — OPERATING INCOME
(GAAP MEASURE) TO GROSS MARGIN (NON-GAAP FINANCIAL MEASURE)
(in thousands)

	THREE MONTHS ENDED
	SEPTEMBER 30,				Increase (Decrease)
	2006		2005		Pretax			After Tax
RECONCILIATION OF REGULATED ELECTRICITY SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	310,440	$	161,845	$	148,595		$	90,569
Plus:
Operations and maintenance		164,396		158,940		5,456			3,325
Real estate segment operations		78,853		67,508		11,345			6,915
Depreciation and amortization		90,390		85,763		4,627			2,820
Taxes other than income taxes		31,697		34,325		(2,628	)		(1,602	)
Other expenses		5,610		13,521		(7,911	)		(4,822	)
Regulatory disallowance		—		143,217		(143,217	)		(87,291	)
Marketing and trading segment fuel and purchased power		80,906		86,945		(6,039	)		(3,681	)
Less:
Real estate segment revenues		97,871		78,755		19,116			11,651
Other revenues		7,167		16,369		(9,202	)		(5,609	)
Marketing and trading segment revenues		84,425		107,031		(22,606	)		(13,778	)
Regulated electricity segment gross margin	$	572,829	$	549,909	$	22,920		$	13,969
RECONCILIATION OF MARKETING AND TRADING SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	310,440	$	161,845	$	148,595		$	90,569
Plus:
Operations and maintenance		164,396		158,940		5,456			3,325
Real estate segment operations		78,853		67,508		11,345			6,915
Depreciation and amortization		90,390		85,763		4,627			2,820
Taxes other than income taxes		31,697		34,325		(2,628	)		(1,602	)
Other expenses		5,610		13,521		(7,911	)		(4,822	)
Regulatory disallowance		—		143,217		(143,217	)		(87,291	)
Regulated electricity segment fuel and purchased power		314,150		203,519		110,631			67,430
Less:
Real estate segment revenues		97,871		78,755		19,116			11,651
Other revenues		7,167		16,369		(9,202	)		(5,609	)
Regulated electricity segment revenues		886,979		753,428		133,551			81,399
Marketing and trading segment gross margin	$	3,519	$	20,086	$	(16,567	)	$	(10,097	)

PINNACLE WEST CAPITAL CORPORATION
NON-GAAP FINANCIAL MEASURE RECONCILIATION — OPERATING INCOME
(GAAP MEASURE) TO GROSS MARGIN (NON-GAAP FINANCIAL MEASURE)
(in thousands)

	NINE MONTHS ENDED
	SEPTEMBER 30,				Increase (Decrease)
	2006		2005		Pretax			After Tax
RECONCILIATION OF REGULATED ELECTRICITY SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	558,800	$	432,502	$	126,298		$	76,979
Plus:
Operations and maintenance		511,155		467,121		44,034			26,839
Real estate segment operations		248,595		190,555		58,040			35,375
Depreciation and amortization		267,308		262,030		5,278			3,217
Taxes other than income taxes		99,970		103,528		(3,558	)		(2,169	)
Other expenses		22,562		39,451		(16,889	)		(10,294	)
Regulatory disallowance		—		143,217		(143,217	)		(87,291	)
Marketing and trading segment fuel and purchased power		227,797		215,347		12,450			7,588
Less:
Real estate segment revenues		318,328		232,950		85,378			52,038
Other revenues		28,173		46,763		(18,590	)		(11,331	)
Marketing and trading segment revenues		259,352		267,460		(8,108	)		(4,942	)
Regulated electricity segment gross margin	$	1,330,334	$	1,306,578	$	23,756		$	14,479
RECONCILIATION OF MARKETING AND TRADING SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	558,800	$	432,502	$	126,298		$	76,979
Plus:
Operations and maintenance		511,155		467,121		44,034			26,839
Real estate segment operations		248,595		190,555		58,040			35,375
Depreciation and amortization		267,308		262,030		5,278			3,217
Taxes other than income taxes		99,970		103,528		(3,558	)		(2,169	)
Other expenses		22,562		39,451		(16,889	)		(10,294	)
Regulatory disallowance		—		143,217		(143,217	)		(87,291	)
Regulated electricity segment fuel and purchased power		735,489		442,532		292,957			178,557
Less:
Real estate segment revenues		318,328		232,950		85,378			52,038
Other revenues		28,173		46,763		(18,590	)		(11,331	)
Regulated electricity segment revenues		2,065,823		1,749,110		316,713			193,037
Marketing and trading segment gross margin	$	31,555	$	52,113	$	(20,558	)	$	(12,531	)