The negative sentiment that gripped pre-market trading to start the new week only got tighter as the day wore on. At its nadir, the Dow had fallen by the largest amount since late October 2020, -946 points. It closed down 725 points, -2.09%, to fall back under 34K again. The S&P 500 dropped -1.58% or 68 points, the Nasdaq was -1.06%, -152 points, and the Russell 2000 -1.5%, -33 points.It’s a big shake-out, no two ways about it. But is it something worse? That’s what investors need to discover as this trading week gets off to a very rough start. The Russell is now -10% off its recent highs, and every stock in the Dow 30 hit the closing bell in the red today. As far as the FAANG stocks, only Netflix NFLX closed slightly higher, ahead of its Q2 earnings release later this week.New Covid-19 scares, particularly the highly infectious Delta variant, have cast a pall over economic growth projections, at least in certain sectors. But today’s sell-off flushed out all sectors — all 11 in the S&P 500 were lower. Because even though regional Covid outbreaks tend to create regional difficulties, if they happen in enough places at the same time, pretty much everywhere has a chance to be negatively affected.For instance, currently the state of Florida claims about 20% of all new Covid infections in the U.S., which is directly hitting the travel industry — especially entities like cruise ships. But the Delta variant is global: in Vietnam, factories are being shuttered at Nike NKE shoe factories, which may face shortages down the road. And on and on: if people begin to stay home again, this will — and has — negatively affect(ed) the Energy space, like ConocoPhillips COP, -3.2%.In a nutshell, markets have now shed all July profits. The Nasdaq is on its longest losing streak — five days — since last October. Could this create a near-term buying opportunity? Of course — especially in those sectors least likely to be negatively hit by a wider resurgence of the pandemic. NVIDIA NVDA was up 3.4% today, for instance. But we enter tomorrow’s market with a shopping list, but not eager to catch a falling knife.Posting Q2 earnings after Monday’s close is IBM Corp. IBM, which beat estimates on both top and bottom lines: $2.33 per share outpaced the $2.25 in the Zacks consensus and $2.18 posted in the year-ago quarter, while revenues of $18.75 billion surpassed the $18.24 billion expected. Cloud & Cognitive Software broyght in $6.1 billion in the quarter and Global Business Services made $4.3 billion.Shares of IBM popped on the news after the bell +3.4%. Shares are up 11.3% year to date but only 10% from this time last year. Though the positive earnings surprise wasn’t really much of a surprise at all: IBM has not missed a consensus earnings estimate since Q3 of 2014.Perhaps this snap-back in IBM shares reflects a buying sentiment going into tomorrow? We shall see.Questions or comments about this article and/or its author? Click here>> 5 Stocks Set to Double Each was hand-picked by a Zacks expert as the #1 favorite stock to gain +100% or more in 2021. Each comes from a different sector and has unique qualities and catalysts that could fuel exceptional growth. Most of the stocks in this report are flying under Wall Street radar, which provides a great opportunity to get in on the ground floor. Today, See These 5 Potential Home Runs >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report NIKE, Inc. (NKE): Free Stock Analysis Report International Business Machines Corporation (IBM): Free Stock Analysis Report ConocoPhillips (COP): Free Stock Analysis Report Netflix, Inc. (NFLX): Free Stock Analysis Report NVIDIA Corporation (NVDA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report