Howard Marks, co-chairman, Oaktree Capital.Courtesy David A. Grogan | CNBCBillionaire investor Howard Marks joined a rising refrain of notable buyers in warning that the market rebound has gone too far given the uphill battle of creating a treatment for Covid-19 and its financial influence in the intervening time.Particularly, Marks believes that markets will ultimately face extra turbulence as soon as the Federal Reserve’s unprecedented, however nonetheless short-term assist mechanisms fade, in accordance with a Bloomberg Information report.”Can the Fed stick with it perpetually?” Marks mentioned in a Bloomberg “Entrance Row” interview. “These of us within the markets consider that shares and bonds are promoting at costs they would not promote at if the Fed weren’t the dominant pressure. So if the Fed had been to recede, we’d all take over as patrons, however I do not assume at these ranges.”The U.S. central bank in March launched into a historic marketing campaign to assist the financial system and monetary markets by a wide range of asset purchases and an announcement of two corporate-credit services with $750 billion in spending energy.The Fed’s coup de grace got here on April 9, when it introduced a $2.Three trillion lending program that can lengthen credit score to banks that situation Paycheck Safety Program loans and buy as much as $600 billion in loans issued by the Primary Road program to medium-sized companies.Optimism concerning the central bank’s efforts grew Sunday evening, when Fed Chairman Jerome Powell spoke of the colossal efforts it is already undertaken and its continued dedication to sustaining U.S. progress.”There’s much more we are able to do” to assist the financial system, Powell advised CBS’ “60 Minutes” in an interview that aired Sunday. “We have accomplished what we are able to as we go. However I’ll say that we’re not out of ammunition by an extended shot. No, there’s actually no restrict to what we are able to do with these lending packages that we now have.”It is these forms of feedback and mammoth financial insurance policies which have reassured some buyers that U.S. enterprise will discover its footing and, slowly however certainly, return to regular. That sentiment, mixed with new hopes over a Covid-19 vaccine, helped catapult U.S. shares larger on Monday with the Dow Jones Industrial Common up 850 factors, or 3.5%, and on tempo for its greatest day since April 6.However skeptics — each of the Fed’s efficiency and of the market rally — stay. Of paramount concern to present market bears is how lengthy it may take for company income to return to progress.Marks says he expects a gradual and halting restoration from the coronavirus pandemic and advised Bloomberg that “there shall be loads” of debt defaults and bankruptcies as firms run out of cash within the months forward.He made related feedback to CNBC in April, when the Oaktree Capital co-chairman mentioned there was a jarring disconnect between the stock market and the fact the world was dealing with amid the Covid-19 outbreak.”We’re solely down 15% from the all-time excessive of Feb. 19,” Marks mentioned on April 20. However “it appears to me the world is greater than 15% screwed up.””Persons are traumatized, and never simply due to the efficiency of their shares,” Marks mentioned on the time. “Everyone’s life is massively modified.”As of Friday, with 90% of the businesses within the S&P 500 having reported outcomes for the primary calendar quarter, earnings are down 13.8% yr over yr, on tempo for the worst slide in income since 2009. The ahead 12-month price-to-earnings ratio, a standard gauge of how “costly” shares are based mostly on their revenue, is 20.3; that is nicely above the 5-year common of 16.7.Others, equivalent to Appaloosa Administration founder David Tepper, agree that the market may be set for extra rocky buying and selling forward. The hedge fund supervisor advised CNBC on Wednesday that the present stock market is among the most overpriced he is ever seen, solely behind 1999.Earlier than Wednesday’s sell-off, it was “possibly the second-most overvalued stock market I’ve ever seen,” Tepper mentioned on CNBC. “I’d say ’99 was extra overvalued.”Fellow billionaire Mark Cuban mentioned on Thursday that he thinks the market is overvalued due to uncertainty surrounding client spending.”I feel it is nearly inconceivable to foretell the place client and company demand goes to return from,” he mentioned. “And due to that, it is arduous to create a valuation for companies.”— Click on right here to learn the unique Bloomberg Information report.Subscribe to CNBC PRO for unique insights and evaluation, and reside enterprise day programming from world wide.