Markets, equity markets, in particular, are at a vulnerable place, today and the rest of this week. That's because the Mega-Cap Tech Darlings that have led the market higher are all at a similar inflection point – live or die, up or down.

What happens, which we'll find out before Friday's close, could delight or devastate markets.

Yesterday, the CEOs of Apple Inc. (NASDAQ: AAPL), Amazon.com Inc. (NASDAQ: AMZN), Facebook Inc. (NASDAQ: FB), and Alphabet Inc.'s (NASDAQ: GOOG) Google – whose companies are all under federal scrutiny – testified before the House Judiciary Antitrust Subcommittee.

That the pandemic meant the whole thing was done via videoconference is just a footnote. Whether our antitrust laws, which were mostly passed or amended between 1890 and 1976, are adequate to address these 21st-century questions and practices, is a story for another day.

Amazon's Jeff Bezos, as The Washington Post noted, hadn't appeared before Congress before, though Mark Zuckerberg, Tim Cook, and Sundar Pichai of Facebook, Apple, and Google are old hat at this by now.

What was said isn't necessarily important – or anything we haven't heard before in one form or another.

It's what happens next – today – that could get interesting.

Why Right Now Isn't Quite Like "Those Other Times"

Although the White House has been leaning on Congress to pursue Big Tech, typically, after a political circus like this, there's no follow-up – nothing really happens – because it's just a show.

But this time might very well be different.

This time, the upcoming election is so important, politicos might actually do something. That is, they may actually put on their "trustbuster" costumes and go after these companies to prove they're doing… something, anything.

Again, ordinarily, that wouldn't necessarily be all that significant. A big settlement here, a few flowery, extracted promises there, everybody moves on with barely a blip.

But, like I said, this time might very well be different.

One the one hand, Big Tech stocks have been sweating a little lately. Trading has been ugly and volatile:

• Facebook fell down – in a New York minute – more than 9% from the all-time highs it just It's a little higher now; it's now got support at $225. It's got to stay there, or it risks further profit-taking.
• Apple, which reports earnings this evening, rose more than 75% off its March lows to make new all-time highs before tanking 8% lower. It's made about half that back, and AAPL shares have support around $350. It needs to hold near there or it's going to see more profit taking, too.
• Amazon's spectacular 106% rise off its lows to new all-time highs… was followed by the stock falling almost 13% in two weeks. Again, it's made roughly half of that back, but Amazon, which also reports after the close today, had better report stellar earnings. If not, it's "Goodbye $3,018" and "Hello $2,800," where it has some support.
• Netflix Inc. (NASDAQ: NFLX) and Microsoft Corp. (NASDAQ: MSFT) – which aren't under the Congressional gun, per se, but certainly under the markets' – are down 11% and 4%, respectively, from their recent all-time highs. NFLX shares need to stay in the neighborhood of $450, and MSFT shares must hold at $200, or, you guessed it, more profit-taking is coming.

So you can see, these stocks, some of the biggest, most widely owned on the planet, and some of the most important to the U.S. economy, are all unusually, uniquely susceptible to profit-taking right now.

Here's Where Stocks Could Go and What We Should Do

With the exception of Netflix, the FAANGs were mostly trading a smidgeon higher yesterday after midday, albeit on somewhat light volume; we're talking about moves of less than 1% here, though Google was up almost 1.4%. Google's earnings hadn't been released at the time of this writing.

They've been under pressure lately, as I said, but generally, these companies are pandemic-resilient – they should be doing better – and they've helped lead markets out of the depths of the March "COVID crash."

That makes them critical, and that makes now critical.

Now, if I were a betting man – and I am a betting man – I'd bet that the tech stocks hold up today and that markets grind higher today and from here.

If that's the case, Big Tech-centric exchange-traded funds like the SPDR Select Technology Sector ETF (NYSEArca: XLK) and the Vanguard Mega Cap Growth ETF (NYSEArca: MGK) will be off to the races, dragging the market along for the ride – whether it wants to go or not.

If, on the other hand, the FAANGs should falter – and I do have my doubts about the bull – well…

Well, what can I say. If that happens, it's not so bad. They won't fall forever – or for too long: It's an opportunity to buy, or, if it's your thing, to dollar-cost average in. We'll be able to add to FAANG positions at lower prices.

And as for the broader market? There are always opportunities out there whether stocks are soaring or tanking.

Of course, I want you to be armed with the most prepared FAANG trading strategy you can get. Riding it out is one option. There are also actions you can take if we do see these tech giants roll over.

Investors holding XLK should think about selling or shorting it if it drops to $105 or below this week. For MGK, the level to watch is $169.

Amazon should be in everyone's portfolio. But if it falls below $2,900 this week, think about taking profits, or even shorting.

Use that same strategy if Apple falls to $370, Facebook to $225, and GOOG to $1,485.

If they don't grind higher right away, I would expect a 3% drop on the small end to a 10-15% drop if selling momentum really picks up and pushes these stocks down over the next couple of weeks.

And I'll tell you when to get back in.

Stay safe out there – I'll be back soon to talk about what today's trading will mean going forward.