This will certainly go down in the books as a really odd year in the markets -- at least for me. We're in the midst of a rally that has lasted more than a year without any notable corrections and, in many sectors, was precipitated by a large number of share repurchases and cost cuts, rather than steady top-line growth.

Yet despite the distrust associated with this rally, the broad-based S&P 500 has rocketed higher by 25% year to date, cruising past its historical average annual gain of 10%. And the S&P 500's performance is only the weighted average of its component stocks, so naturally, some of those blue chips left the index in the dust.

According to data found at Finviz, out of the 6,775 stocks in its database (which covers both major U.S. exchanges and over-the-counter stocks), 540 of them were up 100% or greater in 2013! In other words, at least one in 12 stocks doubled this year!


Source: Herval, Flickr.

Within that subset of 540 companies, a top tier of five stocks stands out among all others. With volatile microcaps and OTC companies removed, these five companies -- which gained a minimum of 570% year to date -- stood at the top of the heap. Let's have a look at what lit a fire under their share prices in 2013 and see if it'll continue next year.

Altisource Asset Management (AAMC -2.60%): 1,000% year-to-date gain
You know the old saying that "the market can stay irrational longer than you can stay solvent"? The people who said that must have had Altisource Asset Management in mind.

Altisource's 1,000% ascent is almost without reason. Positive highlights this year include moving from the over-the-counter bulletin board to the NYSE and continuing to provide asset management services to Altisource Residential Corp. Altisource is also a very thinly traded company, so that appears to have a lot to do with its huge leap in 2013. And finally, insiders and large institutional owners are holding almost 50% of all outstanding shares, of which there are just 2.3 million. 

Beyond that, the reasoning behind this rally fades into oblivion.

Through the first nine months of 2013, Altisource has reported a $2.09-per-share loss on just $30 million in rental revenue and net gains on investments. As a stand-alone asset management company, it has total stockholder equity of $3.5 million and a valuation of $2.1 billion. I would suggest avoiding Altisource altogether in 2014.

Canadian Solar (CSIQ -3.01%): 772% year-to-date gain
Solar shares certainly shined brightly in 2013 as solar-panel pricing finally stopped falling, the Chinese government stepped up and pledged the need for 35 GW of solar power within the country by 2015, and overall global demand picked up.

Canadian Solar, which is actually a provider of solar wafers and modules in China, has been logging a steady stream of contracts. It secured supply orders for four projects in China totaling 100 MW of generating capacity two weeks ago and has been rapidly growing its business in Japan, which accounted for roughly one-third of its sales in the third quarter. Further, Canadian Solar also sold off four of its solar farms in Ontario in order to refocus its efforts on its core Chinese and Japanese markets and raise its cash balance to counter recent loan activity.

While much of the Chinese solar industry is buried under debt and losses, Canadian Solar is back to being profitable on a quarterly basis and could be looking at nearly a 50% expansion in revenue heading into 2014. I'm still a bit gun-shy about Canadian Solar's $719 million in net debt, but with the cash flow expected to roll in next year, I could see it maintaining, or even adding to, its current valuation. 

Corporate Resource Services (NASDAQ: CRRS): 578% year-to-date gain
The reason Corporate Resource Services -- a thinly traded staffing, recruiting, and consulting company -- has rocketed higher this year has to do with the growing number of job openings pushing part-time work, low trading volume that helps amplify its share price gains, and its improving top- and bottom-line growth.

In the third quarter, for example, Corporate Resource Services noted that its revenue grew by 16% over the previous year as it recorded a 216% jump in net income for its fifth straight quarter of profitability.

Unfortunately, as my Foolish colleague Travis Hoium pointed out in February, that only equates to $0.04 per share in profits through the first nine months for a P/E of nearly 90 on a trailing-three-quarter basis. Unless Corporate Resource Services has a rabbit under its hat in 2014, this valuation could wind up being difficult to maintain.

Lannett (LCI): 571% year-to-date gain
Pushing generic-drug manufacturer Lannett higher by 571% this year was a sizable increase in nearly all facets of its generic-drug operations coupled with well-controlled research and development costs.

In Lannett's fiscal first quarter, it delivered a 30% increase in net sales to $45.8 million and drastically revised its guidance to the upside after securing a long-term contract with privately held Jerome Stevens Pharmaceuticals as a distributor for three of its products. This contract allowed the company to boost its full-year revenue guidance to a range of $245 million to $255 million from its prior guidance of $181 million to $186 million, and it boosted Lannett's gross margin forecast by a ridiculous 15 percentage points to 57%-59% from prior forecasts of 43%-44%.

The short story here is that generic drugs often have weaker margins than branded pharmaceuticals, so they need to work harder to get their feet in the door. However, with patented drugs having only a finite patent period, generic-drug makers like Lannett are set up for long-term success so long as they can keep their R&D costs from shooting through the roof. With the baby boomer population aging, I could see a scenario where Lannett has the opportunity to head even higher.

Gray Television (GTN -1.99%): 570% year-to-date gain
Last, but most certainly not least, we have broadcasting company Gray Television, which exploded upward by 570% for the year after going on an acquisition binge that will further help its pricing power and help reduce costs by improving synergies throughout the markets in which it operates.

In early November, Gray purchased three television stations from Yellowstone Television while adding another 12 from Hoak Media and Parker Broadcasting just two weeks later. In addition, many of its peers have been consolidating, which has made Gray a potentially attractive takeover candidate with its revenue picture improving thanks to strong advertising revenue.

Given that Gray Television is valued at just 12 times forward earnings and the political ad season is coming soon for mid-term elections, Gray isn't exactly expensive; but with $790 million in net debt, it's no longer the buy that it was earlier this year, either.