And there didn't seem to be a good reason for it.
There was no news on the wires about this start-up air-taxi service. No upgrades from analysts. Not even a change in a price target -- and yet, the stock price took off.
About the only clue as to why Joby stock was on the move came from a brief alert on TheFly.com, which advised of "bullish option flow" at Joby Aviation. Specifically, TheFly noted that investors had bought five times the "expected" number of call options on Joby stock Friday -- and that purchases of call contracts were outpacing purchases of puts by a ratio of more than 11 to 1.
The most popular calls being bought predict that Joby stock will hit prices of $15 or even $17.50 per share by Oct. 21.
Suffice it to say that this suggests there's a large amount of optimism about where Joby stock is heading. Even a move to just $15 a share would amount to a nearly 14% gain over the next couple of months, while a move to $17.50 would translate to a 32.5% profit for buyers of the stock -- even after Friday's run-up.
Will that happen? Only time will tell, of course, but as I look at Joby now -- a $900 million market cap company with no revenues and a $128 million trailing-12-month net loss -- I can't say I'm terribly optimistic. Investors who have benefited from Friday's inexplicable run-up may be well advised to take their money and run.