Nadex Halts Trading in US Indices Due to Lock Limit Down on August 24, 2015

Nadex has submitted to the Commission on August 24, 2015 an emergency notice pursuant to Commission Rule 40.6(a), that due to the lock limit down in the corresponding underlying markets upon which the Nadex contracts are based, Nadex temporarily halted trading in its US Indices Variable Payout and Binary contracts on the morning of August 24, 2015. Specifically, trading was halted in all US Tech 100 Variable Payout contracts, as well as the Daily and Weekly US Tech 100 Binary contracts, the 2-Hour Intraday Binary contracts with expirations at 10:00am and 11:00am ET, and the 20-Minute Intraday Binary contracts with expirations at 10:00am ET from approximately 8:45am ET until approximately 9:45am ET. Additionally, trading was halted in all Wall Street 30 and US 500 Variable Payout contracts, as well as the Daily and Weekly Wall Street 30 and US 500 Binary contracts, the 2-Hour Intraday Binary contracts with expirations at 10:00am and 11:00am ET, and the 20-Minute Intraday Binary contracts with expirations at 10:00am ET from approximately 9:20am ET until 9:45am ET. Finally, trading was halted in all US SmallCap 2000 Variable Payout contracts, as well as the Daily and Weekly US SmallCap 2000 Binary contracts, the 2-Hour Intraday Binary contracts with expirations at 10:00am and 11:00am ET, and the 20-Minute Intraday Binary contracts with expirations at 10:00am ET from approximately 9:45am ET until 9:55am ET.

The listing of the following contracts was delayed, however, all contracts expired and settled at their normal times:

• 2-Hour Intraday US Tech 100 Binary 11:00am ET Expiration

• 20-Minute Intraday US Tech 100 Binary 10:00am ET Expiration

• 20-Minute Intraday Wall Street 30 Binary 10:00am ET Expiration

• 20-Minute Intraday US 500 Binary 10:00am ET Expiration

• 20-Minute Intraday US SmallCap 2000 Binary 10:00am ET Expiration