What’s up with Vail Resorts’ stock? After a slow and steady decline for the last year, the price last week in a few hours of frenzied trading soared to $145 from $129.

It was the company’s best day on Wall Street in several years, with 2.6 million shares trading hands, about triple the average daily volume. And it was an odd bump, 10 days after the company reported lackluster results from the dismal winter and warned investors that pass sales were slowing. 

The 11% price surge followed reporting by financial journalists at Semafor, citing unnamed sources, that the company has enlisted bankers who specialize in takeover defense. Another Semafor article published June 18, the same day as the sudden stock-price…