The traders kicked off a big week of CNBC's "Fast Money" by addressing increasingly mainstream concerns of a bubble in the equity markets.

With the S&P 500 up more than 23 percent in 2013 and stocks hovering near all-time highs, the "Fast Money" crew reacted to a number of newspaper headlines and bubble quotes from the likes of Bill Gross and other Wall Street heavyweights.

Tim Seymour of EmergingMoney.com said that we're not "terribly bubblicious in terms of the S&P," but added that "you need to be concerned." Ritholtz Wealth Management's Josh Brown expressed similar sentiments, saying, "I was much more comfortable being bullish when people hated stocks.… But there's a lot of room to make money."

Dennis Gartman of The Gartman Letter offered one way to make money: shorting bonds. Addressing long-term U.S. Treasurys, Gartman said he saw "a massive top … I think you have to be selling the bond market at the long end of the curve."

(Read more: Dennis Gartman sees 'massive top' in bond market)

Guy Adami pushed back, saying that the economy may not actually be getting stronger. "I can see in 10 years going back to 2 percent," he said. But Gartman stuck by his thesis, pointing to a stronger-than-expected October jobs number and saying that "outside of New York, things are doing quite well."

A theme emerged on Tuesday, when Jim O'Shaughnessy of O'Shaughnessy Asset Management threw his hat into the bond debate. O'Shaughnessy agreed with Gartman's bearish take on bonds, saying that right now is a "generational selling opportunity" in treasuries.

(Read more: O'Shaughnessy: Crisis in long bonds imminent)

O'Shaughnessy also reiterated a bullish call he made back in 2009, calling for a generational buying opportunity in U.S. equities. "We're now 150 percent greater than when we wrote that," he said, referring to stock market gains since March 2009. "We still think that these numbers are going to continue in this secular trend."

Tesla also drove back into the news Tuesday. CEO Elon Musk addressed concerns over three separate fires in Model S vehicles at The New York Times Dealbook conference, saying, "There's no reason for a recall." Efraim Levy of S&P Capital IQ, who has a sell rating on the stock, joined the "Fast Money" crew Tuesday. "I like the company, the execution has been good, but it's the valuation that's of concern for me," Levy said, regarding his negative rating.

TradeMonster's Adami called the drop in Tesla over the last month "the most meaningful break in the stock since it's become a publicly traded company." Steve Grasso of Stuart Frankel said that he wouldn't get in Tesla right now but would buy the stock if it regains momentum.

Dovish sentiments from Fed chair nominee Janet Yellen kept up the momentum in stocks Wednesday, and retail names took particular focus. Macy's had its best day in four years, and the stock hit new highs on strong October sales and a third-quarter earnings surprise.

(Read more: Beware interest risks from 'Fragile Five': Gemma Godfrey)

But Tom Stemberg of the Highland Consumer Fund wasn't convinced that the Macy's magic would spread to the rest of the retailers. "There are a lot of headwinds here," he said on Wednesday's show, adding that "this is a lousy calendar for retailers." When pressed on whether he'd buy the retail sector as a whole, Stemberg emphatically answered, "absolutely not."

The earnings surprises continued on Wednesday, but for Cisco Systems it was a surprise to the downside. Weak guidance pushed the stock lower by more than 10 percent in the after-hours session.

Brian Marshall of ISI Group called it an "ugly quarter" for the company and said the guidance was "atrocious." But he did point to one silver lining in the report. "They're preserving their margins pretty well. … I think that limits the downside to the EPS," he said.

Dan Nathan of RiskReversal said cost-cutting measures could help Cisco and that a buying opportunity may emerge if the stock were to get oversold.

Despite the mostly negative sentiment surrounding Cisco, one analyst actually upgraded the stock Thursday. Ronnie Moas of Standpoint Research joined the crew to explain his contrarian call. "The stock is trading right now at 8 times earnings when you take out the cash," he said. "This is the time you want to buy Cisco."

(Watch video: Top analyst says: 'Buy' Cisco)

Adami pointed to a key technical level in the stock that helped justify Moas' call. "The levels that we held are the levels that we sort of took off on back in April…this is as interesting as it gets for Cisco." Brian Kelly agreed, saying, "You're not going to get that hurt buying this. … Cisco has some potential to increase their market share."

(Read more: Ex-Fed official apologizes for QE)

Housing stocks were a bright spot Thursday. "We expect to maintain a highly accommodative monetary policy for some time to come," Yellen said during testimony on Capitol Hill. Adami picked Mohawk as his favorite stock in the housing space. Metropolitan Capital's Karen Finerman offered a different way to play housing, namely through brokerage firm Realogy. "They make a fee on every transaction," she said. "The more transactions, the better."

(Watch video: Trulia not for sale, CEO says)

Catch all the action on "Fast Money," weekdays at 5 p.m. ET on CNBC.

—By CNBC's Michael Newberg. Follow him on Twitter: @MikeNewberg.