You need to have a lawyer draw up non-disclosure and/or non-compete documents. Then have your lenders/investors sign them. However, that will alienate some lenders. Risk of someone taking your opportunities is a risk of doing business. It sucks to stick your neck out and risk getting taken advantage of, but sometimes that is the cost of doing business. However, just because a competitor tries to perform the same arbitrage does not mean they will be successful. Finally, the moment you start making money from an arbitrage, the the market will become aware and others will discover it on their own (that is the efficiency of the market).