Investors stand to get about $24.50 a share in Sirius XM stock for each Liberty Sirius XM share—for a 5% return relative to the current price of Liberty Sirius XM—before the effect of the reserve stock split. Put another way, investors can gain Sirius XM stock for about $2.78 a share, which is a discount to the current price.

Except that now that the exact ratio is known (8.375, just slightly lower than the original 8.4) it appears that instead of LSXMA/B/K rising to the arbitrage value, SIRI is dropping to the arbitrage value. And after all those new holders suddenly see SIRI (it'll be new SIRI at $26-$30 after the 1 for 10 split) in their accounts instead of a liberty named stock, they may opt to dispose of it. So there could be a few weeks of consolidation coming up. And then of course, the short trade will end abruptly when "everyone" receives their new SIRI shares to deliver to their lenders. And thus ends my year of lending out SIRI shares at interest rates between 20% and 120% (yes, that's not a typo, shorts were paying me up to 120% annual interest rates for borrowing my SIRI shares recently).