The Hershey Co. candy giant Thursday rejected a takeover bid from Oreo-maker Mondelez International Inc. that would have kept the combined firm's chocolate operations in Hershey, Pa.

But even as the Hershey board was unanimously rejecting the offer, its stock was rising. Hershey shares closed up $16.35 on Thursday - or almost 17 percent - to $113.49. Shares retreated slightly after hours but stayed in that range as analysts speculated that the move on the iconic chocolate company may yet attract more offers.

Mondelez offered $107 a share and a total of $23 billion for Hershey, which has faced slowing growth and remains mostly a U.S. firm.

Investors believe that Mondelez, which makes Cadbury chocolate in Europe and is more international in scope, could bid up to $120 a share or more.

Keith Denninger, an event-driven strategist with the institutional research firm Olivetree Financial in Stamford, Conn., said Mondelez may be seeking a deal because the trust that controls Hershey faces internal turmoil and could be vulnerable to a buyout.

Mondelez also has come under pressure from activist investor William Ackman, who wants the company to increase revenues or sell out. Mondelez, based in Deerfield, Ill., declined comment.

The $12.3 billion Hershey Trust controls about 80 percent of the voting control of the Hershey Co. as the fiduciary for the 2,000-student Hershey School for impoverished children and orphans, the richest private school in the nation.

The Pennsylvania Office of Attorney General is seeking the removal of three trust board members who have served more than 10 years, including chairwoman Velma Redmond and former chairman Robert Cavanaugh, by July 31.

Cavanaugh also holds a seat on the candy company board, as does former Pennsylvania Gov. Tom Ridge.

Mondelez has reportedly said it would change its name to Hershey and run its global chocolate operations from the central Pennsylvania town, according to a report by CNBC. News of a possible offer was first reported by the Wall Street Journal.

Hershey, whose confectionary brands include Reese's, Jolly Rancher, Good & Plenty, Rolo, and Twizzlers, faces its own challenges, including a cutback in sugar consumption by Americans and a relatively small international business as other candy giants have globalized operations.

Seeking to diversify its sugar-based products, Hershey acquired the company that makes and markets Krave jerky in March 2015.

Hershey had sales of $7.4 billion and profits of $512 million in 2015. Stock dividends on Hershey shares help finance the educational programs at the Hershey School.

In 2015, Mondelez reported sales of $29.6 billion and profits of $7.3 billion.

"From a geographic perspective, the move makes sense," Jack Skelly, an analyst with Euromonitor, told Bloomberg News. "Mondelez has achieved its position as the second-largest confectionary manufacturer in the world without a sizable presence in the United States."

But a Mondelez deal for Hershey seems far from certain due to state politics.

In 2002, then-Attorney General D. Michael Fisher and the Dauphin County Orphans Court halted the sale of the Hershey Co. to Wm. Wrigley Jr. Co. for $89 a share when the community and unionized workers protested the deal in the streets.

The company may not rekindle that support, as over the last decade it has closed its big chocolate plant in downtown Hershey and moved those manufacturing operations to Mexico.

The company has retained a manufacturing complex with two factories in Hershey, one that makes milk chocolate and a second that makes Reese's Peanut Butter Cups and Kit Kats.