Goldman Sachs or Mercuria?

Hi all,

I just recently graduated from college. I've always wanted to be a Commodity Trader and work for big trading companies. An opportunity smiled at me for a chance to interview with Mercuria for their trading program. It's fairly early in the process and highly competitive and could take more than a month to find out if you get chosen or not. However, I already got my offer from GS for a general Finance position and I have to answer now. I'm really feeling conflicted and don't know what to do. I feel like either way I'm choosing, I will be left with not knowing what could have happened on the other side. Could you please give me some advice on how to look at it from your experience. Much appreciated!