NEW YORK (Reuters) -Activist investor Irenic Capital Management built a stake in Papa John's during the third quarter, sources familiar with the matter told Reuters on Friday, adding a fresh dimension to mounting speculation about the pizza chain's future.

Generally, when an activist hedge fund builds a new holding, it signals interest in forcing management to consider alternatives. But it was not immediately clear what changes, if any, Irenic will seek at Papa John's. 

A representative for Irenic declined to comment, while a representative for Papa John's did not respond to a request for comment. The size of Irenic's stake was not known. 

The stake could be made public when Irenic makes its 13F filing with the U.S. Securities and Exchange Commission, which requires fund managers to detail their ownership in publicly traded U.S. companies for a given three-month period.

Potential buyers have been circling the pizza chain for months but may have been frightened off as U.S. consumers are pulling back on spending at quick-serve restaurant chains like Papa John's.

Apollo Global recently withdrew an offer to take the chain private at $64 a share, Reuters reported earlier this month, helping send the company's stock tumbling.

With no offer on the table, Papa John's CEO Todd Penegor told analysts on last week's quarterly earnings call that while the board would certainly look at all proposals, it was now moving ahead on executing its own strategy.

Industry analysts and investors said they supported Penegor's candid and pragmatic assessment, helping the stock price recover some.

Its shares seesawed this week after a website called ABC Money published a report on Monday saying there was a new bid for the company, driving its stock north. Its shares tumbled on Tuesday after other media outlets dismissed the story as a hoax. A source close to Papa John's confirmed that the report was false.

Some investors said Papa John's remains a desirable property but given new economic uncertainties, it might take time for potential bidders to come to an appropriate price.

Irenic was founded by former Elliott Investment Management executive Adam Katz and former Indaba Capital Management executive Andy Dodge and has been involved when companies like Arconic, Barnes and Couchbase went private and mounted activist engagements at News Corp and Theravance Biopharma.