Are investors in Plug Power (PLUG 12.29%) stock irrationally exuberant?

Yesterday, shares of the hydrogen fuel cell manufacturer surged to close 26% higher after announcing an expanded strategic collaboration with Australian partner Allied Green Ammonia, whereby the two companies will build a $5.5 billion green chemical production facility in Uzbekistan, and there produce electrolyzer to create hydrogen fuel. Today, Plug Power stock is up another 16% through 10:15 a.m. ET.

Are any other catalysts fueling Plug Power's rise?

Image source: Getty Images.

Plug CFO's big buy

Turns out, there are. Yesterday, I was unimpressed by Plug's announcement of the Uzbekistan project, which Plug boasted created a "5 GW partnership now spanning two continents" between itself and Allied Green Ammonia. After all, the companies' Australian project hasn't yet received a "final investment decision," while the Uzbekistan deal is in even earlier stages.

It all seems very hypothetical to me.

Plug Power's own CFO, Paul Middleton, though, seems to see things differently. In a sterling example of putting money where one's mouth is, Middleton yesterday purchased an additional 650,000 Plug Power shares on the open market, the same day the Uzbekistan deal was announced.

Priced at $1.03 per share, that's a $672,000 bet that Plug Power stock is the real deal. And to drive the point home, Middleton added, "This additional investment reflects my strong conviction in Plug's strategy and long-term value creation."

Is Plug Power stock a buy?

Still, there are other ways to view Middleton's investment. Middleton already owned nearly 2 million Plug shares before yesterday's purchase, which are now worth $0.43 per share more than they were worth last week. His net worth just jumped by more than $800,000.

If nothing else, yesterday's news just created a lot of value for Plug's CFO.