AeroVironment Inc. shares jumped 14 percent Wednesday on news that an activist Newport Beach hedge fund had acquired a 5.1 percent stake in the Monrovia maker of unmanned drone aircraft and electric-car charging stations.

Engaged Capital, an investment firm specializing in small- and mid-cap companies in North America, now owns about 1.6 million shares. According to regulatory filings, it began acquiring its stake in November. The purchases make it the third-largest shareholder, after Chief Executive Tim Conver and L.A. mutual fund giant Capital Group Cos. Inc.

Engaged said in a press release that AeroVironment’s share price could be boosted with better corporate governance and financial disclosures, a stronger capital structure and renewed focus on capital allocation.

“In our view, concerns over an excess of cash in the capital structure, a lack of granularity and specificity with respect to its growth plans, and uncertainty surrounding its heavy exposure to the defense budget are all addressable issues,” Glenn Welling, Engaged’s principal and chief investment officer, said in a statement.

In its own statement, AeroVironment, which also has operations in Simi Valley, noted that the company has an experienced board of directors that regularly evaluates the company’s capital structure and capital allocation priorities so as to “support growth initiatives without compromising our ability to make quick and decisive strategic investments in emerging opportunities.”

That being said, the company said it “welcomes open communications with all of its stockholders and values their input towards the goal of enhancing stockholder value.”

Pentagon budget cuts have slowed the pace of orders for AeroVironment drones, and sluggish adoption of electric cars in United States has stunted growth in its car-charger unit. The company announced job cuts in May, and last month reported it had moved to a loss in its fiscal fourth quarter.

Shares at one point been were down 20 percent from the first of the year, but have recovered in recent weeks, and before today’s news were off only 7 percent from the beginning of the year.

AeroVironment shares closed up $2.92, or 14 percent, to $23.57 on the Nasdaq.