It’s been a shaky week for the “high five” tech stocks, which toppled again Thursday before rebounding a bit in pre-market futures trading Friday. However, today’s “quadruple witching” could cause swings in volatility, potentially sowing confusion about any possible gains for tech or other sectors.

There’s also big news from the corporate world to digest this morning after Amazon.com, Inc. (NASDAQ: AMZN) announced that it’s buying Whole Foods Market, Inc. (NASDAQ: WFM) for $13.7 billion. Shares of other grocery stores fell after the announcement. As others leave “brick and mortar,” AMZN has taken a huge step into that space. The deal also looks like it might represent an interesting play on millennial eating habits, including the trend toward fresh, organic foods and cooking at home rather than eating out.

Quadruple witching only happens four times a year, and involves the simultaneous expiration of stock futures, stock index futures, stock options, and single stock futures. This often means elevated volume and volatility at the open and at the close, so market participants might want to watch out for that. It’s also sometimes associated with position unwinding and shifting of positions between sectors, so even if tech stocks do make a comeback today, it might be difficult to say if it’s a trend or just quirky movements that sometimes happen on this once-a-quarter witching day.

Arguably the biggest story of the last week aside from the Fed is pressure on the so-called “high five” tech stocks. These five stocks — Facebook Inc (NASDAQ: FB), Alphabet Inc (NASDAQ: GOOG) (NASDAQ: GOOGL), Apple Inc. (NASDAQ: AAPL), Microsoft Corporation (NASDAQ: MSFT), and Amazon — account for two-fifths of the S&P 500’s (SPX) rise so far this year, as a quick read of any financial media web site will tell you.

Keep things in perspective. Most tech stocks haven’t participated in the recent pullback. Looking at the big five, a lot of the recent pressure seems to be profit taking and some re-assessment after a long rally that’s taken them to record levels. Fundamentals still appear pretty positive, though we’ll find out more starting about a month from now when earnings season gets underway in earnest.

Aside from info tech and quadruple witching, the other major focus today might end up being crude oil, which closed at seven-month lows before edging up early Friday to just under $45 a barrel. The $44.50 level continues to be one to watch, as it appears to be holding for now. It could be hard for the stock market to keep going higher, however, if oil continues to drag.

In other commodity action, gold took a beating Thursday due in part to strength in the dollar that came after the Fed raised rates. Gold prices popped back a little early Friday.

With this week’s Fed meeting over, it’s time once again to look out for Fed speakers. Dallas Fed President Robert Kaplan will be the first Fed official to deliver remarks since the Fed raised interest rates on Wednesday, speaking in Dallas at 12:45 p.m. ET.

Economic data Thursday delivered some decent news, with industrial production for May coming in flat, as Wall Street analysts had expected, but April industrial production ticking up a notch to 1.1% from the previous 1%. Initial weekly jobless claims of 237,000 were below analysts’ expectations, and both the June Philadelphia Fed and the June Empire Manufacturing surveys outpaced predictions. Empire Manufacturing, in particular, looked very strong. Housing starts data reported early Friday, though, were below Wall Street’s estimates.

Biotech stocks edged downward yesterday after media outlets reported that the Trump White House is considering an executive order aimed at lowering drug prices. The Nasdaq Biotech Index fell nearly 1% on the day, but has been relatively flat the last three months or so. Financials took a step back after rising Wednesday in the wake of the Fed meeting, and the defensive utilities sector led all sectors, though industrials were right behind.

From a technical perspective, support for the SPX is between 2385 and 2401, said research firm CFRA.

FIGURE 1: SOFT COMMODITIES? With crude oil having taken it on the chin this month, and gold on a two-day post-Fed slide, commodity indices, such as the Bloomberg Commodity Index, are hitting their worst levels of the year. Data source: Bloomberg. Chart source: The thinkorswim® platform from TD Ameritrade. For illustrative purposes only. Past performance does not guarantee future results

Commodities sliding.

Commodity indices such as the Bloomberg Commodity Index ($BCOM, see Figure 1 above) are hitting their lowest levels of the year. The index is comprised of a basket of commodities including energy, grains, industrial and precious metals, soft commodities, and livestock. This comes after a number of bearish reports, most recently the Energy Information Administration’s weekly supply report, which showed gasoline stocks having risen unexpectedly. That followed last week's reported buildup of crude supplies. Meanwhile, a somewhat hawkish tone from the Federal Open Market Committee (FOMC) after this week's meeting, plus the Fed's acknowledgement of lower inflation, sparked a two-day selloff of gold and other metals.

Balance Sheet Plans Seem Opaque

Many market participants had hoped the Fed would give details about the unwinding of the balance sheet, like how much and how soon and at what pace. But the Fed was vague, only saying it will start to shrink its holdings gradually sometime this year. That gives the Fed a lot of leverage to shrink the balance sheet as it sees fit, but doesn’t provide much visibility to market participants who want to know more about the timing and extent of the move. So the market is likely going to continue to seek out more details from the Fed, potentially making Fed Chair Janet Yellen’s future press conferences more important.

Defensive Strength

Financials and industrials both posted gains after the Fed decision — though financials fell Thursday — but so did utilities, one of the so-called “defensive” sectors. Some of the utilities’ advance might be associated with the sinking 10-year bond yield, which was up slightly early Friday but still below 2.2%. At this point, at least, dividend-paying stocks don’t face much competition from bond yields, as they started to earlier this year when 10-year yields climbed to 2.6%. The low bond yields continue to make dividend stocks look attractive to some investors. One thing to watch, however, is whether bond yields start to recover a bit — as they did Thursday — amid Fed talk about reducing its balance sheet starting later this year. That move could inject more debt into the market, perhaps causing bond prices to fall and yields to rise accordingly.

See more from Benzinga

• Fed Reaction: Markets Knew What Was Coming And Behaved Accordingly

• Not Much Sense Of Mystery: Fed Meeting Begins With Rate Hike Widely Expected

• Tech Stocks Under Pressure As New Week Highlighted By Fed Meeting Begins

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