It's not a mystery. The spread between A and B actually blew out to about 20% yesterday afternoon in the middle of the panic. The long CY/short SPWR trade has been an unsuccessful hedge fund favorite for a long time, so when you see the Yen carry and other carry trades unwind amidst all the deleveraging (hedge funds take position size down when crazy times are happening), it makes sense that you wouldn't expect the spread to close right away; there's not a lot of arbitrage money left to come into SPWR.

The 60.75 close for SPWR/SPWRA yesterday, and the 59.86 close for SPWRV/SPWRB yesterday represent only the closing cross on the Nasdaq. The spread between the two was never very small before that, and it hasn't been less than 5 points today, but it is MUCH less than it was yesterday afternoon, and it will continue, on average, to narrow over time.

No serious institutional investor with his head on straight will be establishing new positions in SPWRA at this point. What you're going to see is this spread close gradually over time--maybe a couple of days, maybe weeks, maybe months, but it will come in.

BOTTOM LINE, buy B for new positions. And, if you are a tax-free investor, sell your A and buy B. I wouldn't advise any of you to go out and short the A, unless you are willing to risk the pain of having it ripped out from under you if your broker is forced to cover.