Nadex binary options don't have rebates on losing trades, but if you buy an option at 50, and it drops to 30, you can sell it for a partial loss, instead of waiting for it to drop to 0 (or move above 50, which would produce a profit). Ultimately though, at expiry, the Nadex option will be worth 100 or 0. Therefore, when determining your risk you must assume the worst case scenario. 
1)    Choose Your Broker Wisely: With each passing month, droves of newcomers, both veteran traders and beginners alike, rush to open at binary option trading account, based primarily on an Internet advert. The appeal of this new trading vehicle has also generated an army of new brokers on a monthly basis, each sporting the latest and greatest trading platform, asset portfolio, or payoff ratios. In the early days, these brokers originated in far off tax havens where gambling casinos were legal, but in the last few years, traditional brokers have begun to join the fray, finally accepting that binary options were not some fad. As a result, the competition is great, and, unfortunately, the conditions are ripe for a fair share of fraudulent brokers to exist and for many to employ very shady business practices. Take your time finding the right broker for you. Check with your local regulator, other traders, and Internet review websites for any irregularities or a rash of negative comments. Your time spent here will be the best investment you can make for the long run.
I am sorry but Mr. Harrison obviously knows nothing about binary options trading. Has anybody bothered to examine his article? Example: III – Basic Options Strategy “Your 30 minutes call option wins and the 15 minutes put option losses. You will have earned $185 from the 70% call winnings and the 15% consolation refund from the put option (the opposite can happen, put option wins and call option losses).” Absolute nonsense. You invest $200 in total (2x 100). So if one trade wins and the other loses, your RETURN will be $185 (170 from the winner and 15 from the… Read more »

The expiry time is the period that your placed contract is expected to expire. It is the period between the time you place the trade and the time it expire. For most brokers in the industry, the trader is allowed to choose his or her preferred expiry period while opening a trade. The expiry period could be as short as 60 seconds or as long as days or even months.

The FBI estimates that the scammers steal $10 billion annually worldwide.[11] The use of the names of famous and respectable people such as Richard Branson to encourage people to buy fake "investments" is frequent and increasing.[12] Articles published in the Times of Israel newspaper explain the fraud in detail, using the experience of former insiders such as a job-seeker recruited by a fake binary options broker, who was told to "leave [his] conscience at the door".[13][14] Following an investigation by the Times of Israel, Israel's cabinet approved a ban on sale of binary options in June 2017,[15] and a law banning the products was approved by the Knesset in October 2017.[16][17]