‘Just a couple of quarters’ left for JCP?

Foundering retailer J.C. Penney needs "a big turnaround" and is running out of time to get it right, Macquarie's Liz Dunn said Thursday.

Asked who might be able to turnaround the company's fortunes, Dunn said it was difficult to say.

"That's premature," she said. "It's hard for me for me to react to that, but I think it would need to be someone who has experience with sort of the moderate-income consumer, has experience with couponing, has experience with merchandising and marketing and can really be a confidence-inspiring leader for the vendor community and the lender community."

(Read more: JC Penney looking for new CEO to replace Ullman: Sources)

Dunn added that it might not be easy to find a new chief executive.

"It definitely would be a big challenge," she said. "I don't know that anyone who's sitting in a cherry seat right now would want to take on this leadership position and potentially redefine their own legacy."

Sources told CNBC that the company was looking for a new CEO to replace Mike Ullman, who took the helm after the departure of former Apple executive Ron Johnson.

Former CEO Allen Questrom said on "Fast Money" that he would consider returning under the right conditions.

(Read more: Questrom's return would give JCP more time: Josh Brown)

"He's a retail legend, and I think that is very positive news, but we've got a lot to do between now and when a new CEO will be named," Dunn said. "I think they've just got a couple of quarters more before things start to get really bad for them, so it's a quick turn that needs to be executed here, and we don't even have a CEO name who's going to replace Ullman."

But even the possible return of Questrom wasn't enough to improve the outlook for the company, she added.

"I'm still waiting and watching," Dunn said. "If Allen Questrom does come back as chairman, I do think that's going to be a positive for the vendor community and just something that will shore up their confidence, but really this is a big turnaround that they need to execute."

She said a new CEO faced substantial obstacles.

"I think some of the capital improvements they've made to the store are actually hindering their ability to turn the business around because the store is kind of configured in weird ways that don't lend itself to selling what they traditionally sold," Dunn said. "I'm not any more confident today hearing this news."

—By CNBC's Bruno J. Navarro. Follow him on Twitter @Bruno_J_Navarro.

Trader disclosure: On Aug. 8, 2013, the following stocks and commodities mentioned or intended to be mentioned on CNBC's "Fast Money" were owned by the "Fast Money" traders: Joe Terranova is long GS; Joe Terranova is long MS; Joe Terranova is long VRTS; Joe Terranova is long OXY; Joe Terranova is long TRV; Joe Terranova is long EMC; Joe Terranova is long SJM; Joe Terranova is long TRIP; Joe Terranova is long SBUX; Joe Terranova is long URBN; Joe Terranova is long HOS; Joe Terranova is long AXP; Joe Terranova is long PXD; Joe Terranova is long EOG; Joe Terranova is long CXO; Joe Terranova is long LTD; Michael Murphy is long AAPL; Josh Brown is long AAPL; Josh Brown is long FSLR; As of 8/7 Jon Najarian is long AAPL; Jon Najarian is long CIE; Jon Najarian is long POT; Jon Najarian is long PBR; Jon Najarian is long MAR; Jon Najarian is long HUN; Jon Najarian is long HLF; Jon Najarian is long FCS; Jon Najarian is long puts JCP.