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
	DECEMBER 31,					Increase (Decrease)
	2006		2005			Pretax			After Tax
RECONCILIATION OF REGULATED ELECTRICITY SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	60,070	$	82,787		$	(22,717	)	$	(13,846	)
Plus:
Operations and maintenance		180,122		168,706			11,416			6,958
Real estate segment operations		76,266		87,811			(11,545	)		(7,037	)
Depreciation and amortization		91,336		85,622			5,714			3,483
Taxes other than income taxes		28,425		28,512			(87	)		(53	)
Other expenses		5,853		12,536			(6,683	)		(4,073	)
Regulatory disallowance		—		(4,655	)		4,655			2,837
Marketing and trading fuel and purchased power		62,840		77,744			(14,904	)		(9,084	)
Less:
Real estate segment revenues		81,470		105,081			(23,611	)		(14,391	)
Other revenues		7,999		14,458			(6,459	)		(3,937	)
Marketing and trading revenues		71,390		84,098			(12,708	)		(7,746	)
Regulated electricity segment gross margin	$	344,053	$	335,426		$	8,627		$	5,259

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

	TWELVE MONTHS ENDED
	DECEMBER 31,				Increase (Decrease)
	2006		2005		Pretax			After Tax
RECONCILIATION OF REGULATED ELECTRICITY SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	618,870	$	515,289	$	103,581		$	63,133
Plus:
Operations and maintenance		691,277		635,827		55,450			33,797
Real estate segment operations		324,861		278,366		46,495			28,339
Depreciation and amortization		358,644		347,652		10,992			6,700
Taxes other than income taxes		128,395		132,040		(3,645	)		(2,222	)
Other expenses		28,415		51,987		(23,572	)		(14,367	)
Regulatory disallowance		—		138,562		(138,562	)		(84,454	)
Marketing and trading fuel and purchased power		290,637		293,091		(2,454	)		(1,496	)
Less:
Real estate segment revenues		399,798		338,031		61,767			37,647
Other revenues		36,172		61,221		(25,049	)		(15,267	)
Marketing and trading revenues		330,742		351,558		(20,816	)		(12,687	)
Regulated electricity segment gross margin	$	1,674,387	$	1,642,004	$	32,383		$	19,737
RECONCILIATION OF MARKETING AND TRADING GROSS MARGIN
Operating Income (closest GAAP measure)	$	618,870	$	515,289	$	103,581		$	63,133
Plus:
Operations and maintenance		691,277		635,827		55,450			33,797
Real estate segment operations		324,861		278,366		46,495			28,339
Depreciation and amortization		358,644		347,652		10,992			6,700
Taxes other than income taxes		128,395		132,040		(3,645	)		(2,222	)
Other expenses		28,415		51,987		(23,572	)		(14,367	)
Regulatory disallowance		—		138,562		(138,562	)		(84,454	)
Regulated electricity segment fuel and purchased power		960,649		595,141		365,508			222,777
Less:
Real estate segment revenues		399,798		338,031		61,767			37,647
Other revenues		36,172		61,221		(25,049	)		(15,267	)
Regulated electricity segment revenues		2,635,036		2,237,145		397,891			242,515
Marketing and trading gross margin	$	40,105	$	58,467	$	(18,362	)	$	(11,192	)