Activist investor Jana Partners LLC's Barry Rosenstein and Jeff Smith's Starboard Value have new significant positions in Jack in the Box Inc. (JACK - Get Report) , raising the prospects that a boardroom battle or spinoff of the fast-food restaurant chain could be next.

The Deal, a sister publication to The Street, in May reported that Jack in the Box could become an activist target after it announced that it was exploring options for its Qdoba Restaurant Corp. Mexican restaurant chain.

Now, Jana Partners revealed Tuesday that it had accumulated a $134 million position in the restaurant chain between July and September. On Monday, Starboard Value revealed it had accumulated $18 million worth of JACK shares over the same period.

Starboard Value or Jana Partners track records suggest that either could launch a campaign to drive share price improvement change at Jack in the Box if a Qdoba sale or spinoff doesn't occur. Smith's fund has launched 138 campaigns at 110 different companies since 1999, including a jaw-dropping 62 director-election battles, according to FactSet Inc. And Jana Partners has launched 57 campaigns including eight proxy fights since 2001.

In addition, the New York Post reported earlier this month that buyout shop Apollo Global Management, owner of Chuck E. Cheese, is close to acquiring the 720-location chain for as much as $500 million.

Activists often push companies to spin off or sell businesses. A sale generates cash that can be used for share buybacks and dividends. A spinoff creates a new publicly-traded company for investors to own stakes in. Insurgents also often push for restaurant chains to franchise more locations, something an activist fund could agitate for at Jack in the Box. A move by Jack in the Box not to complete a Qdoba transaction could result in a Starboard or Jana Partners boardroom battle in 2018.

Jack in the Box reports its fourth quarter fiscal 2017 earnings on Nov. 30. 

Another insurgent, Keith Meister of Corvex Management, reported in May that it had accumulated a 1.8% position, about $56 million worth of shares. But the fund subsequently liquidated its position.

Separately, Jana Partners also accumulated new positions in the third quarter in Cornerstone OnDemand inc. (CSOD - Get Report) , D.R. Horton Inc. (DHI - Get Report) , Lululemon Athletica (LULU - Get Report) , Oracle Corp. (ORCL - Get Report) , Osprey Energy Acquisition (OSPR) , UnitedHealth Group Inc. (UNH - Get Report)  . It liquidated positions in Blue Apron (APRN - Get Report) , Cognizant Technology Solutions (CTSH - Get Report) and Hewlett Packard Enterprises (HPE - Get Report) , among other positions. 

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