In all due respect Major, I don't believe that the large, multiple offers of ECU shares is related to an "arbitrage" with AUMN stock. Perhaps, if an investor wants to purchase ECU and AUMN/20 can be acquired cheaper, then it is justifiable.
In the 7/6/11 trading, there were isolated offers of 100,000 shares which would require simultaneous bids of 5000 shares of AUMN if one were attempting to capture "free money," and I don't believe bids of that size existed. Most of the transactions of AUMN were merely 100 shares although sometimes several trades occur simultaneously but are split into 100 lots for some strange reason.
I think the "shorts" are attempting to cover and are currently willing to pay C$.92, Wednesday's primary executed price. I also suspect that in order to prevent the stock from rallying (and making it more expensive to cover), the same entities are placing very large offers just above C$.92 to discourage bidders from driving the stock higher.
The "proof" would occur if some very large bids developed and the large offers suddenly disappeared, but I don't think we will get that level of buying until outstanding MSZ drill results are reported!
Silverbull50