What a month November was. All the major stock market indices made new all-time highs, and the S&P 500 index managed to muscle its way 4.4% higher during the month, a breakneck annualized pace.

Any reasonable investor would understandably think that this is a pretty attractive time to own stocks overall. But they'd be wrong.

That's because, despite the bullish price action in the S&P last month, more than a third of the individual stocks in the big index actually declined during November. Many of those declined by a lot. Nearly half of the S&P components that declined in November actually underperformed the rest of the index by 10% or more for the month.

The takeaway here is that we're stuck in the middle of two stock markets right now. And while one of those markets is charging higher in the final stretch of 2016, the other could be toxic for your portfolio.

To figure out which stocks to steer clear of, we're turning to the charts today for a technical look at five stocks that could be toxic for your portfolio in the month ahead.

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 -- and when to sell them.

DuPont Fabros Technology

So much for the strong start to the year for shares of $3 billion datacenter real estate investment trust DuPont Fabros Technology (DFT) . While shares of DFT are up more than 24% since the start of January, that's in spite of the recent price action, not because of it. Since peaking in July, DFT has lost more than 17% of its market value -- and shares are signaling the potential for even lower ground this week.

DFT is currently forming a descending triangle pattern, a bearish continuation setup that points to the possibility of more downside risk in shares. Basically, as DFT bounces in between those two technically significant price levels, shares have been getting squeezed closer and closer to a breakdown through that $38 support line. If and when that happens, we've got our sell signal.

Relative strength, which measures DFT's performance versus the rest of the broad market, has been an extra piece of evidence against this stock in recent months. DFT's relative strength line has been making lower highs as shares have underperformed the broad market in the second half of 2016, and that downtrend in relative strength is still intact here, making this stock statistically likely to underperform going forward. If $38 gets violated, DFT becomes a sell.

Public Storage

It shouldn't come as a huge surprise that another REIT is leading our list of potentially toxic trades. The prospect of higher interest rates has been putting pressure on any assets with high yields -- and Public Storage (PSA - Get Report) is another casualty. So far, shares are down 16% this year, and like with DFT, a textbook example of a descending triangle is signaling the potential for even lower ground ahead. For Public Storage, the big breakdown level to beware of is support at $202.50.

What makes that $202.50 level in particular so significant? It all comes down to buyers and sellers. Price patterns, like this descending triangle setup in Public Storage, are a good quick way to identify what's going on in the price action, but they're not the actual reason it's tradable. Instead, the "why" comes down to basic supply and demand for shares of the stock itself.

The $202.50 support level in Public Storage is a place where there has been an excess of demand for shares this month; 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 $202.50 so significant - the move means that sellers are finally strong enough to absorb all of the excess demand at that price level. If PSA violates $202.50, we've got a new signal that sellers are still in control of shares.

American Tower

American Tower (AMT - Get Report) has fallen into the "toxic" category lately. This mobile infrastructure stock first crossed our radar in early November, when shares started looking "toppy" after climbing 10.6% on a total returns basis. Now, after violating support and giving about half of that performance back, American Tower is worth a second look.

The price setup in play in American Tower was a simple one: a double top. The double top looks just like it sounds. It's formed by a pair of swing highs that peak at approximately the same price level; the low that separates those two highs is the line in the sand that, if violated, triggers the sell. For American Tower, that happened up at $107.50.

The question investors should be asking here is whether now's a buying opportunity on the dip, or whether AMT still looks toxic. From a price target standpoint, based on the minimum measuring objective of the double top that triggered in November, American Tower's violation of $107.50 signals support down around $97.50, a price level that acted like a short-term floor for shares as recently as March. That, combined with the recent surge of downward momentum we saw this week, means that we probably haven't seen the end of AMT's selling yet. Caveat emptor.

Eni 

The energy sector has been one of the notable winners lately, with an uptrend that's accelerated on the heels of the announcement that OPEC will cut oil supply by 1.2 million barrels per day. But not all oil and gas stocks are in breakout mode here. In fact, Italian energy giant Eni (E) looks like one that you'd best avoid.

The price action is pretty straightforward in Eni right now -- you don't need to be an expert trader to figure out why you don't want to own it. Eni has been harangued by a well-defined downtrend since mid-June, bouncing its way lower on every test of the top of that price range. Shares are bumping their head at $29 resistance this week, potentially setting off the eighth consecutive failure at trendline resistance. The next bounce lower is the signal that it's time to sell.

Frankly, even if Eni manages to muster the strength to pull off an about-face, change its trend, and break out through the top of its price channel here, it's an energy stock to avoid in 2016. That's because a tepid breakout looks a whole lot less compelling when the rest of the sector is exploding higher, as it is now. Until Eni ceases to be a laggard, don't buy it.

Alphabet 

Finally, there's tech giant Alphabet  (GOOG - Get Report) (GOOGL - Get Report) . The entire tech sector has been trading lower in the last month, and Alphabet has been leading it there. While this $512 billion internet giant started off November on a strong note, shares are rolling over in the long term. From here, a classic bearish price pattern is teetering on the edge of a breakdown.

Alphabet is currently forming a head and shoulders top, a reversal pattern that signals exhaustion among buyers. The head and shoulders 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 triggers when Alphabet's neckline gets materially violated. That happens at the $745 level in GOOG. Shares are testing a breakdown through that price level today.

Alphabet is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells GOOGL? Learn more now.

It's important to remember to be reactionary with Alphabet, just like with any of the other technical trades on our list of potentially toxic stocks. Even though the setup looks negative, the sell signal doesn't actually come until GOOG violates $745 and sellers officially retake control of this stock. But until we get a definitive price reaction here, buyers should hold off on adding to positions.

At the time of publication, the author had no positions in the stocks mentioned.