The following is interesting.
When they talked about nationalizing the company, everyone dumped their shares:
YPF 6-month chart (Daily)
And then it hit 10.13, which seems to be a 52-week low, and Slim and Co. pick up shares at 10.
Then the people hear the news about Slim picking up shares and the share price jumps to 12.50 range (probably because of Slim's buy), and then everyone else, it seems, who was waiting to dump this worthless stock, dumps their stock, bringing the price back down to 11.17 (which is more reasonable but still way too high).
Here's the 10 day chart (15-minute)