@jeremyp
TBH, I'm not even sure how much more he could possibly manipulate the share price.
The biggest jump in stock value was when he had bought those 9.2% of the shares, starting with a jump of about 25% and ending up about 27% over the previous share price. Then it started to decline. Between his announcement that he wants to buy it, and Twitter accepting, it barely rose back to about the level from after he bought those shares.
AND his offer included a 1 billion penalty if he backed out, which he probably thought would be the only money he'd lose for the stunt. Turned out, it didn't work that way.
BUT even more importantly, remember this wouldn't be the only stock he stood to win or lose from. The kerfuffle promptly caused the price of Tesla stock to drop, lowering his own worth by about 30 billion dollars.
So, yeah, I'm seriously not sure how much more he thought he could manipulate Twitter share price to make up even for that 1 billion penalty.
TL;DR: I think even you give him way more credit than he deserves. I seriously think he's a clown who tried to pull a stunt that would give him publicity. The guy seems seriously more obsessed with being in everyone's mind all the time than Tinkerbell.