Wall Street best hope that a Bernie Sanders win in the Iowa caucus is a mere flash in the pan. Because if Sanders becomes the Democratic nominee and were to beat Trump — which is not out of the realm of possibilities (see the 2016 election outcome) — a combo of a President Sanders and Treasury Secretary Elizabeth Warren could do a number on the Federal Reserve.Speculation is picking up in some political circles that seeking to consolidate the Democratic vote early, Sanders would offer banking hawk Warren the coveted Treasury Secretary spot. That would place two Wall Street hawks in charge of — among other things — selecting the next Federal Reserve chief and possibly re-shaping how the monetary policy body governs. And to be sure, their choice for Fed head would very likely be the opposite of current Fed Chair Jerome Powell.Think not so stock market friendly.“Perhaps Warren could win, perhaps Warren could be Treasury Secretary. The question is the Fed is more relevant. As long as you have someone in there as more of a moderate — certainly Powell is there for now —investors will feel some comfort there,” pointed out FBB Capital Partners director of research Mike Bailey on Yahoo Finance’s The First Trade.The market’s comfort in Powell — after a rocky start to his tenure — stems from a repeated stance on being data dependent on interest rate policy. That led to three rate cuts in 2019 as the Fed sought to prop up growth amid the U.S.-China trade war. Markets are pricing in at least one more rate cut later this year.The Powell Fed has also injected liquidity into repo markets to relieve funding pressures. Wall Street pros believe the quantitative easing like effort coupled with the three rate cuts have lit the fuse of stocks for the better part of the past year.Federal Reserve Chair Jerome Powell speaks during a news conference following the Federal Open Market Committee meeting in Washington, Wednesday, Jan. 29, 2020. (AP Photo/Manuel Balce Ceneta)MoreSanders and Warren haven’t hidden their dislike for the Fed. They have tended to attack the institution itself in public forums, more so than Fed chiefs. That would suggest the potential for a broader overhaul of how the Fed operates under positions of increased authority for Sanders and Warren.”Banking industry executives must no longer be allowed to serve on the Fed’s boards and to handpick its members and staff,” Sanders wrote in a 2015 New York Times op-ed titled “Bernie Sanders: To rein in Wall Street, fix the Fed.”Sanders added, “Board positions should instead include representatives from all walks of life — including labor, consumers, homeowners, urban residents, farmers and small businesses.”As for Warren, she has voiced contempt for how the Fed handles bank mergers saying they are done in a “backroom.”“Your approval process in itself appears to be a rubber stamp. Everything is happening behind closed doors,” Warren proclaimed to Powell during a 2019 Senate hearing. Warren’s comments stemmed from the $66 billion merger of SunTrust and BB&T, a deal which has since been completed.“Market sentiment towards Sanders has shifted lately. Two weeks ago, his surging popularity was interpreted as a negative, because many of his policies are not stock market friendly. However, now the market’s opinion on Sanders is starting to change, where markets might welcome a Sanders candidacy, seemingly with the idea that he would not win against Trump,” says Sevens Report Research founder Tom Essaye.For Wall Street, Essaye better be right.Brian Sozzi is an editor-at-large and co-anchor of The First Trade at Yahoo Finance. Watch The First Trade each day here at 9:00 a.m. ET or on Verizon FIOS channel 604. Follow Sozzi on Twitter @BrianSozzi and on LinkedIn.Read the latest financial and business news from Yahoo FinanceMicrosoft CEO Satya Nadella on the future of retail4 major concerns investors have about the stock market in 2020Trump’s tax plan will hurt restaurants again in 2020: Dunkin’ chairWatch: Target is Yahoo Finance’s ‘Company of the Year’Beyond Meat founder: things are going very well with McDonald’sStarbucks CEO on what China has in store for the coffee giantFollow Yahoo Finance on Twitter, Facebook, Instagram, Flipboard, SmartNews, LinkedIn, YouTube, and reddit.