United states securities and exchange commission

1. Weighted-average per share.
The aggregate intrinsic values in the table above represent the total pretax intrinsic value (the difference between the closing stock price on the last trading day of 2017 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their in-the-money options at year end.
At December 31, 2017 , $24 million of total unrecognized pretax compensation cost related to stock options is expected to be recognized over a weighted average period of 1.86 years. Total intrinsic value of options exercised for the period September 1 through December 31, 2017, was $19 million , and DuPont realized tax benefits from options exercised of $6 million .
DuPont RSUs and PSUs

DuPont issues non-vested RSUs that serially vest over a three -year period and, upon vesting, convert one -for-one to DowDuPont Common Stock. A retirement eligible employee retains any granted awards upon retirement provided the employee has rendered at least six months of service following the grant date. Additional RSUs are also granted periodically to key senior management employees. These RSUs generally vest over periods ranging from two to five years. The fair value of all stock-settled RSUs is based upon the market price of the underlying common stock as of the grant date. The awards have the same terms and conditions as were applicable to such equity awards immediately prior to the Merger closing date.

DuPont grants PSUs to senior leadership. Upon a change in control, DuPont's EIP provisions required PSUs to be converted into RSUs based on the number of PSUs that would vest by assuming that target levels of performance are achieved. Service requirements for vesting in the RSUs replicate those inherent in the exchanged PSUs.
Vesting for PSUs granted in 2016 and 2017 is based upon total shareholder return ("TSR") relative to peer companies. Vesting for PSUs granted in 2015 is equally based upon change in operating net income relative to target and TSR relative to peer companies. Operating net income is net income attributable to DuPont excluding income from discontinued operations after taxes, significant after-tax benefits (charges), and non-operating pension and other postretirement benefit costs. Performance and payouts are determined independently for each metric. The actual award, delivered as DowDuPont Common Stock, can range from zero percent to 200 percent of the original grant. The weighted-average grant-date fair value of the PSUs granted in 2017, subject to the TSR metric, was $91.56 , and estimated using a Monte Carlo simulation. The weighted-average grant-date fair value of the PSUs, subject to the revenue metric, was based upon the market price of the underlying common stock as of the grant date.
In accordance with the Merger Agreement, PSUs converted to RSU awards based on an assessment of the underlying market conditions in the PSUs at the greater of target or actual performance levels as of the closing date. As the actual performance levels were not in excess of target as of the closing date, all PSUs converted to RSUs based on target and there was no incremental benefit from the Merger Agreement when compared with DuPont’s EIP.
In November 2017, DowDuPont granted PSUs to senior leadership that vest partially based on the realization of cost savings in connection with cost synergy commitments, as well as DowDuPont’s ability to complete the Intended Business Separations. Performance and payouts are determined independently for each metric. The actual award, delivered in DowDuPont Common Stock, can range from zero percent to 200 percent of the original grant. The weighted-average grant date fair value of the PSUs granted in November 2017 of $71.16 was based upon the market price of the underlying common stock as of the grant date.

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At December 31, 2017 , $113 million of total unrecognized pretax compensation cost related to RSUs and PSUs is expected to be recognized over a weighted average period of 1.73 years.
Nonvested awards of RSUs and PSUs are shown below.

DuPont RSUs and PSUs	2017
Shares in thousands	Shares		Weighted Average Grant Date Fair Value
Nonvested at Sep 1, 2017	3,948		$	67.06
Granted	412		$	70.02
Vested	(139	)	$	67.67
Canceled	(23	)	$	66.65
Nonvested at Dec 31, 2017	4,198		$	68.28

The total fair value of RSUs and PSUs vested from September 1 through December 31, 2017 was $9 million . The weighted average grant-date fair value of stock units granted during 2017 was $70.02 .

NOTE 21 - FINANCIAL INSTRUMENTS

The following table summarizes the fair value of financial instruments at December 31, 2017 and 2016 :

Fair Value of Financial Instruments at Dec 31	2017												2016
In millions	Cost			Gain			Loss			Fair Value			Cost			Gain			Loss			Fair Value
Marketable securities 1	$	4		$	—		$	—		$	4		$	—		$	—		$	—		$	—
Other investments:
Debt securities:
Government debt 2	$	637		$	13		$	(11	)	$	639		$	607		$	13		$	(12	)	$	608
Corporate bonds	704			32			(3		)	733			623			27			(5		)	645
Total debt securities	$	1,341		$	45		$	(14	)	$	1,372		$	1,230		$	40		$	(17	)	$	1,253
Equity securities	164			2			(26		)	140			658			98			(50		)	706
Total marketable securities and other investments	$	1,509		$	47		$	(40	)	$	1,516		$	1,888		$	138		$	(67	)	$	1,959
Long-term debt including debt due within one year 3	$	(32,123	)	$	69		$	(2,121	)	$	(34,175	)	$	(21,091	)	$	129		$	(1,845	)	$	(22,807	)
Derivatives relating to:
Interest rates	$	—		$	—		$	(4	)	$	(4	)	$	—		$	—		$	(5	)	$	(5	)
Commodities 4	$	—		$	130		$	(256	)	$	(126	)	$	—		$	56		$	(213	)	$	(157	)
Foreign currency	$	—		$	31		$	(159	)	$	(128	)	$	—		$	84		$	(30	)	$	54