8. Other Income

The components of other income for the three months and six months ended June 30, 2017 and 2016 were:



	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016

	(in millions)
Market data fees	$	9	$	8	$	18	$	17
Account activity fees		5		5		10		9
Risk exposure fees		6		4		11		9
Payments for order flow		4		3		8		7
Gains on financial instruments, at fair value and other investments, net		—		16		2		51
Gains from currency diversification strategy, net		29		17		78		101
Other, net		6		4		8		7
	$	59	$	57	$	135	$	201

Market data fees are charged to customers for market data services they subscribe to and are largely offset by the related costs paid to obtain market data from third party vendors. Account activity fees are charged to customers that do not generate the minimum monthly commission. The fee is the difference between the minimum required commission and the actual commissions generated. Risk exposure fees are earned from a small minority of customer accounts carrying positions with market risk that exceeds defined thresholds. Payments for order flow are earned from various options exchanges based upon options trading volume originated by the Operating Companies. Gains on financial instruments, at fair value and other investments, net include (1) realized and unrealized gains and losses on financial instruments that (a) are held for purposes other than the Company’s market making operations, (b) are subject to restrictions, or (c) are accounted for under the equity method and (2) dividends on investments accounted for under cost method.