To answer a few interbankfx questions:
Are the spreads fixed at 2 pips EUR/USD on news reports? Yes. And just to illustrate, spreads were 2 pips on EUR/USD all during NFP on Friday - the mother of all news reports. That is the only pair I follow but the demo mirrors the live account so you can see the spreads there yourself if you are interested.
How can they offer that spread without being a market maker? They have a superior business model to the traditional spot forex dealer. They act as broker getting paid for every trade being made out of the spread. Their liquidity providers are actually banks, who provide the fills and quotes, and who presumably rebate back a portion of the spread to IBFX for facilitating trade. In this regard, IBFX does not take an adversarial role against their clients, unlike so many of the popular spot FX dealers in this industry.
How does their margin work? Margin for a mini contract is $50 per (10K) contract and $1000 per (100K) standard contract. You can readily see that this will give you a much higher effective margin rate than 200% at full margin on a mini account trading EUR/USD because the EUR/USD price is not taken into account. At the current EUR/USD price of 1.25 that is an effective 250% margin rate on a mini account or 125% on a standard account compared with how Oanda or IdealPro calculates maximum margin for EUR/USD.
Interest? Interest is charged/paid (by way of the swap column in the software) at 5:00 PM Eastern time. Close out positions before that time and no interest is charged / accrued. Some have complained that the swap fees are excessive but I don't typically have positions on at that hour so I have not been effected. Best suggestion is to open a demo account and test out holding positions at that hour to see what type of cost / interest you might receive for your trading strategy.
how do gaincapital or IB IDEAL PRO ?
compare to interbankfx? I don't know about Gain capital. With IB IdealPro you trade any size over 25K USD with 1 unit increments. With IBFX you trade in mini lots of 10K with a mini acct, or standard lots of 100K with standard account. IdealPro spreads vary 1-2 pips on EUR/USD + commission. IBFX has the commission built into a 2 pip fixed EUR/USD spread. With IdealPro you can step inside the bid/ask and be a price maker. You cannot do this with IBFX - can only trade at the posted bid/ask. Much higher leverage is available with IBFX. As far as I can tell, no interest is paid on cash balances with IBFX, but paid from Interactive Brokers on amounts over 10K. My experience is both are very honest and trustworthy. I am a satisfied customer of both. I don't know why no info on IBFX's principals is available. IBFX is much smaller than IB so IBFX's principals are more accessible (right off the phone menu). Accounts at Interactive Brokers are insured but not at InterbankFX. Both are registered with the NFA / CFTC.
Seth: How does Gain capital compare to IdealPro?
IBFX holds almost nightly webinars where you can get answers to many questions, and see how their software works. Their customer service is excellent. Fills are also good. The link for webinars is on their home page.