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
	JUNE 30,				Increase (Decrease)
	2006		2005		Pretax			After Tax
RECONCILIATION OF REGULATED ELECTRICITY SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	191,197	$	178,832	$	12,365		$	7,536
Plus:
Operations and maintenance		168,332		153,097		15,235			9,286
Real estate segment operations		98,412		67,713		30,699			18,711
Depreciation and amortization		89,297		85,323		3,974			2,422
Taxes other than income taxes		32,700		34,638		(1,938	)		(1,181	)
Other expenses		8,430		17,556		(9,126	)		(5,562	)
Marketing and trading segment fuel and purchased power		72,716		57,593		15,123			9,217
Less:
Real estate segment revenues		112,603		84,259		28,344			17,276
Other revenues		9,782		20,259		(10,477	)		(6,386	)
Marketing and trading segment revenues		89,925		71,172		18,753			11,430
Regulated electricity segment gross margin	$	448,774	$	419,062	$	29,712		$	18,109
RECONCILIATION OF MARKETING AND TRADING SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	191,197	$	178,832	$	12,365		$	7,536
Plus:
Operations and maintenance		168,332		153,097		15,235			9,286
Real estate segment operations		98,412		67,713		30,699			18,711
Depreciation and amortization		89,297		85,323		3,974			2,422
Taxes other than income taxes		32,700		34,638		(1,938	)		(1,181	)
Other expenses		8,430		17,556		(9,126	)		(5,562	)
Regulated electricity segment fuel and purchased power		263,944		160,590		103,354			62,994
Less:
Real estate segment revenues		112,603		84,259		28,344			17,276
Other revenues		9,782		20,259		(10,477	)		(6,386	)
Regulated electricity segment revenues		712,718		579,652		133,066			81,104
Marketing and trading segment gross margin	$	17,209	$	13,579	$	3,630		$	2,212

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

(in thousands)

	SIX MONTHS ENDED
	JUNE 30,				Increase (Decrease)
	2006		2005		Pretax			After Tax
RECONCILIATION OF REGULATED ELECTRICITY SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	248,360	$	270,657	$	(22,297	)	$	(13,590	)
Plus:
Operations and maintenance		346,759		308,181		38,578			23,513
Real estate segment operations		169,742		123,047		46,695			28,461
Depreciation and amortization		176,918		176,267		651			397
Taxes other than income taxes		68,273		69,203		(930	)		(567	)
Other expenses		16,952		25,930		(8,978	)		(5,472	)
Marketing and trading segment fuel and purchased power		146,891		128,402		18,489			11,269
Less:
Real estate segment revenues		220,457		154,195		66,262			40,387
Other revenues		21,006		30,394		(9,388	)		(5,722	)
Marketing and trading segment revenues		174,927		160,429		14,498			8,837
Regulated electricity segment gross margin	$	757,505	$	756,669	$	836		$	509
RECONCILIATION OF MARKETING AND TRADING SEGMENT GROSS MARGIN
Operating Income (closest GAAP measure)	$	248,360	$	270,657	$	(22,297	)	$	(13,590	)
Plus:
Operations and maintenance		346,759		308,181		38,578			23,513
Real estate segment operations		169,742		123,047		46,695			28,461
Depreciation and amortization		176,918		176,267		651			397
Taxes other than income taxes		68,273		69,203		(930	)		(567	)
Other expenses		16,952		25,930		(8,978	)		(5,472	)
Regulated electricity segment fuel and purchased power		421,339		239,013		182,326			111,128
Less:
Real estate segment revenues		220,457		154,195		66,262			40,387
Other revenues		21,006		30,394		(9,388	)		(5,722	)
Regulated electricity segment revenues		1,178,844		995,682		183,162			111,637
Marketing and trading segment gross margin	$	28,036	$	32,027	$	(3,991	)	$	(2,432	)