U.S. markets are reacting to the Brexit vote results early this morning, after a flurry of global market activity leading up to last night's referendum.

This week has been a big one for the S&P 500 so far. In the last four sessions, the big index has added 2% to its price tag, coming back within grabbing distance of the all-time highs set last year. A lot of that price action has been in anticipation of Thursday's Brexit vote.

And now, with the final results in and the speculative bets over, the question is what happens to stocks from here. While around 90% of S&P 500 components have moved higher in the past week, correlations are likely to come back to earth now that the big binary Brexit event is over. That means we'll likely return to the market of leaders and laggards that's been the standard mode for stocks in 2016.

More important, the laggards are likely to make up for lost time following this week's upside move. They're the stocks you definitely don't want to own as we head into the final week of June.

To find the stocks waving red flags here, we're turning to the charts today for a technical look at five big stocks that could be toxic to own.

For the unfamiliar, technical analysis is a way for investors to quantify qualitative factors, such as investor psychology, based on a stock's price action and trends. Once the domain of cloistered trading teams on Wall Street, technicals can help top traders make consistently profitable trades and can aid fundamental investors in better entry and exit points.

Just so we're clear, the companies I'm talking about today are hardly junk. By that, I mean they're not next up in line at bankruptcy court -- and many of them have very strong businesses. But that's frankly irrelevant to what happens to their stocks; from a technical analysis standpoint, sellers are shoving around these toxic stocks right now. For that reason, fundamental investors need to decide how long they're willing to take the pain if they want to hold onto these firms in the weeks and months ahead. And for investors looking to buy one of these positions, it makes sense to wait for more favorable technical conditions (and a lower share price) before piling in.

So without further ado, let's take a look at five toxic stocks to sell.

Deutsche Bank

Leading off the list is German banking giant Deutsche Bank  (DB - Get Report) . 2016 has been a pretty awful year for shareholders of Deutsche Bank. Shares have lost 26% of their market value since the calendar flipped to January, underperforming the big market indices by a big margin. But zoom out on the chart and Deutsche Bank's price trajectory is still showing some big red flags; shares are forming a classic continuation pattern in the long term.

Deutsche Bank is currently forming a descending triangle pattern, a bearish price pattern that signals more downside ahead. The pattern is formed by horizontal support down below shares at $15, and downtrending resistance to the top-side. Basically, as Deutsche Bank bounces in between those two technically important price levels, this stock has been getting squeezed closer and closer to a breakdown through support. When that happens, we've got our sell signal.

There's an extra red flag showing up on Deutsche Bank's chart: It's relative strength, an indicator that measures this stock's price performance versus the rest of the stock market. Not surprisingly, this stock's relative strength line has been in a downtrend since last summer, signaling that Deutsche Bank is still continuing to underperform the rest of the market long-term, even despite the recent rebound in share prices. If $15 gets violated, look out below.

Telefonica 

We're seeing a similar (and just as long-term) pattern in shares of another stock with big Eurozone exposure: Spanish telecom company Telefonica (TEF - Get Report) . Just like Deutsche Bank, Telefonica is currently forming a long-term descending triangle pattern, in this case with a key support level down at $9.50.

Why all of the significance at that $9.50 level? It all comes down to buyers and sellers. Price patterns, like this descending triangle setup in Telefonica, are a good quick way to identify what's going on in the price action, but they're not the actual reason a stock is tradable. Instead, the "why" comes down to basic supply and demand for shares of the stock itself.

The $9.50 support level in Telefonica is a place where there has been an excess of demand for shares; in other words, it's a spot where buyers have been more eager to step in and buy shares than sellers have been to take gains. That's what makes a breakdown below $9.50 so significant -- the move would mean that sellers are finally strong enough to absorb all of the excess demand at that price level. Buyer beware.

Mobile TeleSystems

Another overseas telco, $8 billion Russian phone company Mobile TeleSystems  (MBT - Get Report)  is showing some cracks this week too -- only this stock hasn't been under pressure in 2016, unlike Telefonica. Instead, Mobile TeleSystems is actually coming off a stellar start to the year, up more than 38% so far in 2016. But that rally is beginning to show some cracks this summer. And shareholder might want to start thinking about taking those gains off the table.

That's because Mobile TeleSystems is currently forming a rounding top, a simple bearish reversal pattern that looks just like it sounds. The rounding top indicates a gradual shift in control of shares from buyers to sellers. In Mobile TeleSystems' case, the sell signal comes on a violation of this pattern's support level at $8.50. This stock is flirting with a breakdown through that price level this week.

Price momentum is an extra signal that the buying pressure is waning in Mobile TeleSystems. That's because 14-day RSI, our momentum gauge for this stock, rolled over back in April, and it's been making lower highs ever since. That adds a lot of downside confirmation to this stock once $8.50 gets busted.

Vector Group

As simple as the rounding top in Mobile TeleSystems may look, it's hard to get more straightforward than the price pattern we're seeing right now in shares of cigarette stock Vector Group (VGR - Get Report) . Vector has been a "sell the rips" stock since last fall -- and shares are bumping their head on a long-term price ceiling once again this week.

Since last November, Vector has been bouncing its way lower in a downtrending channel, a price range that's corralled most of this stock's price action incredibly well. Put simply, every test of trendline resistance has given sellers their best opportunity to get out before this stock's subsequent leg lower. And shares are testing that price ceiling for a fifth time now. From here, the sell signal comes on the next bounce lower.

Waiting for a bounce before clicking "sell" is a critical part of risk management for two big reasons: It's the spot where prices are the highest within the channel, and alternatively it's the spot where you'll get the first indication that the downtrend is ending. Remember, all trend lines do eventually break, but by actually waiting for the bounce to happen first, you're confirming that sellers are still in control before you unload shares of Vector Group.

Novo Nordisk

Last up on our list of potentially toxic trades is a stock we looked at earlier this month: $108 billion pharmaceutical giant Novo Nordisk  (NVO - Get Report) . When we last looked at Novo Nordisk, this stock was teetering on the edge of a head and shoulders top, a bearish reversal setup that signals exhaustion among buyers.

The head and shoulders in Novo Nordisk is formed by two swing highs that top out at approximately the same level (the shoulders), separated by a higher high (the head). The sell signal came on a move through Novo's neckline, just above at the $53 level. Since this stock first made our list of "toxic stocks," shares have lost nearly 9% from peak to trough -- but Novo has been rebounding more recently. The question now is how to trade it.

At this point, investors should be looking at the recent rebound in Novo Nordisk with some skepticism. That's because what we're seeing so far is a pullback to this stock's neckline, a price move that often comes when a recent breakdown trade moves up to re-test newfound resistance before making a more meaningful leg lower. Until Novo can catch a bid above the pattern's top up at $57, sellers are still in control.

Disclosure: This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.