2017 has been full of new developments for investors. Some of these were foreseeable, while others weren't so much. So just were some of those trends exactly?

Bitcoin

The first and perhaps most obvious is bitcoin. At the start of the year, bitcoin prices were around $1,000. By August, bitcoin was still a hot topic, even though prices were still below $3,000. Even there though, it was almost a triple for the digital currency, an impressive move not many were expecting.

But by September, prices were almost at $5,000. Two months later and it was almost $7,000 -- up seven-fold from the start of the year. By December, $20,000 was a real possibility. The trend in digital currencies has sparked massive moves all over the place as well. Ethereum, bitcoin cash, litecoin, ripple and dozens of others started rocketing higher too.

I wasn't old enough to be investing during the dot-com bubble in the early 2000s. While we've seen big runs in certain stocks or industries in recent years, none felt like an actual bubble -- until cryptocurrency came along. While bitcoin may very well have a purpose in the future, it's hard to argue the bubble-like qualities that have come with it. Heck, bitcoin alone was up almost 20-fold at its highs this year.

If a company so much as mentions a foray into bitcoin or blockchain, the stocks have rallied hundreds or even thousands of percent. Just look at Riot Blockchain (RIOT) , a supposed former biotech company that took a small stake in a Canadian cryptocurrency exchange and rallied some 1,000% as a result. Then there's Long Island Iced Tea (LTEA) , which quickly surged 200% after changing its name to Long Blockchain Corp. -- yes, seriously. Even companies like Square (SQ) saw huge surges in their stock price just by allowing select users to buy and sell bitcoin.

Like I said, I wasn't around during the tech bubble, but this looks awfully bubbly to me. Just like tech didn't disappear during the collapse, crypto probably won't either. But this seems like too much, too fast.

Semiconductors

Given the wide-spreading reach that semiconductors touch, it's no surprise that this group has done so well in 2017. Names like Micron (MU) , Nvidia (NVDA) , Intel (INTC) , Skyworks Solutions (SWKS) , Lam Research (LRCX) , Qorvo (QRVO) and many others have all done incredible. This came after a strong 2016 campaign for many names too.

While some cooled off -- like Advanced Micro Devices (AMD) -- it was foolish to think that the tech sector would suddenly need less of these products. Going forward, is it likely that this shift changes?

No.

Companies continue to push the boundaries when it comes to technology, as seen in self-driving cars and artificial intelligence. Demand for NAND and DRAM remains strong, which is good news for Micron and Lam Research.

Further, continued strong sales of video game systems -- like the Nintendo (NTDOY) Switch, Sony (SNE) Playstation and Xbox (from Microsoft (MSFT) ) -- along with smartphones and other electronic gadgets should continue to propel component sales higher as well. (And man, just look how well gaming stocks have performed!)

While the rallies in stocks like Nvidia and Intel may seem stretched, the secular themes they're riding remain strong. The valuations for Skyworks, Micron and others is also quite low, which may allow these stocks to gravitate higher provided the underlying trends stay in place.

Industrials, Aerospace

Another big theme has been in the resurgence of blue-chip, old-school U.S. stocks. While the first that comes to mind may be the dreadful performance of General Electric (GE) , tons of others have done stellar this year.

Look no further than Boeing (BA) , which is up about 90% so far this year. It's no surprise then to see stocks like Honeywell (HON) up 33% and United Technologies (UTX) climbing 16.5%. Defense has been hot too, with Lockheed (LMT) , Rockwell Collins (COL) and Northrop Gruman (NOC) all doing well.

But it's not just aerospace and defense that's been hot, all sorts of industrials have been too. Everything from Caterpillar (CAT) and Deere (DE) , up 70% and 52%, respectively, to 3M Co. (MMM) , which has rallied 32% so far in 2017.

Some of these have been big-time duds over the years but are finally starting to feel some love. It's only natural to wonder if this group will come down in 2018. Of course it's possible to see a correction, but the longer term themes -- be it in defense with North Korea, aerospace with increased air-travel demand or with industrials as infrastructure spending rises -- remain in place for many of these companies.

Nvidia, Microsoft, Lockheed, General Electric and Honeywell are holdings in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Jim Cramer buys or sells NVDA, MSFT, LMT, GE and HON? Learn more now.

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

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