I think the "guaranteed" profit would be long TSLA and short SCTY. If merger goes through, SCTY jumps 20% but your TSLA is hedged against this jump, so no risk here. If merger falls, TSLA jumps and SCTY file Chapter 11 and you get a lot of profit. If you long SCTY and short TSLA, if the merger goes through, you gain nothing; if not, you loss a lot.At this point, the divergence between SCTY and TSLA is so much no one dares to enter arbitrage anymore because everyone's fearing everyone else knows more. I suppose part of the problem is for a guaranteed profit, you need to buy SCTY and short TSLA. My guess is that the latter is what is keeping investors from going forward with it.
Interesting times even for being at the sidelines. First, if the squeeze happens, and then what's next? Who's going to blink and take profit? Who's going to make their shares available for lending again? Are there new/old shorts then stopping up to the plate to try to drive the stock back down again? Or will they be afraid to be hit by a GAAP-profitability (pre)announcement? Exciting!
Maybe this is the reason why there's a big difference in shares price. Long TSLA and short SCTY is almost a risk free trade.