Erm, are you guys forgetting smth? The future of the reference rates for BOTH of the legs of these wondrous spreads is uncertain. If the various regulators and committees have their way, by 2021 there will only be one rate to rule them all. Obviously, it's all complicated, but this joy and excitement might be, sadly, short-lived. Still, I applaud the CME for finally doing something like this. There are certain really pesky technical issues with the way LOIS basis is currently traded (not cash, as this ain't a TED spread, but rather two cleared OTC derivative contracts) and this should hopefully fix them (mostly, issues related to convexity, as well as daycount and compounding conventions). To be sure, LIBOR-OIS basis is VERY different to treasury asset swap spreads, so Mav is incorrect, cash doesn't dominate this mkt. LOIS and other unsecured term basis mkts are reasonably large and they all trade, at least for now. Why don't they do LIBOR/GC spread futures instead? At least, they will have a future (pun intended).