that is a 2.39% return and it does not include other fees such as sending fee (wire transfer fee $40) and reeving fee ($15) and buying fee (commission rate).
Edit:
Example 1: let's say you place $100/BTC order and Bitcoin price goes below $1. You will receive 1 Bitcoin.
Example 2: if Bitcoin prices goes above $100 then you will receive certain percentage on price increase and not full profit. So it is best to invest it yourself.
The 2.39% is the actual return, the OP annualized this rate to assume you would continue to get this rate over a year. Regardless this is likely not a legit investment opportunity (even if you ignore the costs involved). The return is simply too high
There is a conversion between btc to usd when you invest, otherwise you don't pay brokerage for maximiser.
As far as the credibility goes, Coinarch shows their faces on their website, goes to conferences, and participates in bitcoin panels.
https://www.coinarch.com/Info/AboutCoinarchhttps://plus.google.com/113776688557331719084/postshttps://www.facebook.com/coinarch