The year 2018 officially wound up as the worst year for investors since the 2008 financial crisis, with the S&P 500 ending the year with around a 5% drop on a total-returns basis. But the good news for investors is that the technical picture actually points to the possibility of a rebound in 2019.

Now, part of the reason for growing investor anxiety has to do with the fact that 2018's fourth quarter saw a pretty constant stream of selling pressure. Since the calendar flipped to October, stocks have shed about 14% of their market value -- the worst fourth quarter since the financial crisis.

But check out this chart, which shows the S&P 500's weekly performance since 2012:

It doesn't take a technical analyst to figure out that the prevailing trend for the index during this period has been upward. Heck, if someone came up to you with this chart right now and asked if you wanted to own it, your answer would probably be a very quick: "Yes!!!"

The troubling short-term deterioration that we've seen in stock prices actually looks much more like a bull-market correction when viewed over this longer term. In fact, the price action that we're seeing right now looks a lot like mid-2015, when the S&P 500 saw a similar pair of volatility shocks -- violating a short-term uptrend. But then the index successfully held its secular trendline as 2016 began.

So, if 2015 ends up being a fair proxy for 2018's market action, then there's plenty of reason for investors to celebrate as 2019 begins. After all, the 24 months that followed the end-of-2015 correction wound up being a stellar time to own stocks.

Of course, that doesn't guarantee what's to come for equities. The S&P 500 could certainly violate its long-term uptrend, opening downside risk as demand for shares fizzles.

However, as long as the S&P 500's trendline support holds at around the 2,400 level (the index closed Monday at 2,506.85), then the high-probability trade for early 2019 is a rebound move.

(This column has been updated.)

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