Arbitrage opportunity without any risk?

[bytemaster]

In the coming new btsx market with interest, suppose I short 10,000 bitUSD at price A, and bid bitUSD at the the price, so I will get 10,000 bitUSD, but with 10,000*2*A btsx in collateral. In this case, no matter the price of btsx goes higher or goes lower, my total asset balance will not change. But, I am getting interest due to holding bitUSD. It seems that this is better than just holding btsx, but I doubt this is sustainable. What did I mistake?

Your mistake was that you can only do that *if*:
1) the price you short at is the "median price feed"
2) there are no other shorts competing with you
3) all USD for sale below the median feed has been consumed

Good luck

[ripplexiaoshan]

In the coming new btsx market with interest, suppose I short 10,000 bitUSD at price A, and bid bitUSD at the the price, so I will get 10,000 bitUSD, but with 10,000*2*A btsx in collateral. In this case, no matter the price of btsx goes higher or goes lower, my total asset balance will not change. But, I am getting interest due to holding bitUSD. It seems that this is better than just holding btsx, but I doubt this is sustainable. What did I mistake?