Arbitrage is only when the deal is assured and the big fast...

Arbitrage is only when the deal is assured and the big fast players quickly takes away all arbitrage in a true market.   I think the price difference tells us about the risk the RMS offer does not go through.  If the market is always right then you have an equal chance of making the 8c per 4xEXU shares as losing the 8c if the RMS offer does not go through, that is EXU drops 2c.

Looking at the EXU price falling to about 8c like before the new RMS offer is a 3c loss so you could think the market is pricing in a 1/3 risk that the ALK offer is accepted.  Something like that anyhow...