CHICAGO (Reuters) - Shares of Hershey Co (HSY.N: Quote, Profile, Research) rose more than 9 percent on Tuesday on renewed speculation the company could hook up with one of its remaining rivals -- such as Cadbury or Nestle -- in order to compete with a merged Mars and Wrigley.

The future of Hershey, the No. 1 U.S. chocolate maker, has been the occasional source of speculation for several years, with the latest threat to its market position being the April 28 news that Mars Inc would acquire Wm Wrigley Jr Co WWY.N to create the world's No. 1 confectionery company.

On Tuesday, analysts at Sanford Bernstein said in a research note that Hershey's options were reduced to a joint venture with Kraft Foods Inc (KFT.N: Quote, Profile, Research) or Nestle SA (NESN.VX: Quote, Profile, Research) and said that Hershey "operates a mass-market chocolate business in a slow-growth mature market."

Hershey is scheduled to meet with analysts next month to discuss its strategic plans under David West, who took over as chief executive last year.

"The merger between Mars and Wrigley has forced Nestle to rethink its confectionary business. Some people anticipate that Hershey will make an announcement in the near term with another confectionery company like Cadbury or Nestle," said William Lefkowitz, options strategist at brokerage firm vFinance Investments.

Analysts speculated in April that the Wrigley-Mars deal could force chocolate and chewing gum maker Cadbury PLC (CBRY.L: Quote, Profile, Research) to reconsider a tie-up with Hershey.

An outright acquisition of Hershey is unlikely as the Hershey Trust, which controls about 78 percent of Hershey's voting shares, has said that Pennsylvania law requires it to maintain control of Hershey.

A spokesman for the Hershey Trust could not be reached for comment.

"There's been no indication that the trust has had a change of heart," Edward Jones analyst Matt Arnold said.