NEW YORK (MainStreet) — Launched on January 1, 2013, the 21 companies listed on the marijuana stock index are a good place for investors to explore jumping on the cannabis bandwagon.

"I'm not making recommendations, but rather I launched the index to educate and inform investors about marijuana stocks because they are risky and speculative," said Fred Fuld who constructed the index and launched it on

To be listed on the marijuana stock index, companies must have some sort of significant connection to marijuana and be in business for more than a year. The index excludes cannabis stocks that trade below a penny.

"Investors can use the index is to determine which stocks are suitable to invest in as well as to see how the industry is performing as a whole," said Fuld who is based in Concord, Calif.

For all intents and purposes, the marijuana stock index has outperformed the S&P 500. Since January 1, 2014 when marijuana was legalized in Colorado, the S&P 500 is up 0.4% compared to 10.6% for the marijuana index and as of January 1, 2013, the S&P 500 is up 20% while the marijuana index is up 385%.

"The marijuana stock index is a great way to keep track of this hot, emerging sector, which is outperforming the major indices right now," said Timothy Sykes, entrepreneur and penny stock expert in Miami. "But time will tell if these stocks can hold their gains because I am far from convinced that will happen."

Trading on the NASDAQ stock exchange, Psychemedics (PMD) is the only stock in the marijuana index that is paying a dividend yield at 4.0%.

"This company provides marijuana and drug testing services but it's uncertain how legalized marijuana will effect their business, because they provide services to law enforcement agencies that request testing," Fuld told MainStreet. "If marijuana is legal, that's one less drug people will need to be tested for."

Newer additions to the list include electronic cigarette companies that are now offering marijuana electronic cigarettes and hemp oil electronic cigarettes. They include VaporBrands International (VAPR), Vape Holdings (VAPE) and mCig (MCIG), which is up 600% from 5 cents to 35 cents a share since the new year. "These companies are extremely speculative and very low cap," Fuld said.

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The stock in the index that has risen the most since January 1, 2014 is Plandai Biotechnology (PLPL), a penny stock that's up 3,460% from 5 cents a share a year ago to $1.68 through February 11, 2014.

"The increase could be a result of a pump and dump where an investor acquired a lot of the shares and sent out emails to thousands of people saying this is a great stock, because it has dropped from $2.41 on February 1 to $1.68 today," said Fuld.

Pumping and dumping involves artificially inflating the price of an owned stock through false and misleading positive statements in order to sell the cheaply purchased stock at a higher price.

"Pump and dump is common for a lot of the penny stocks on the index except for a few high quality stocks that generate earnings and those are involved in the medical marijuana side of the business," said Fuld.

The safer and more staid blue chip stocks listed on the index are the medical marijuana companies GW Pharmaceuticals (GWPH), Solvay SA (SVYZY) and Valeant Pharmaceuticals International (VRX).

Trading at $135.64 a share with a market capitalization of $47 billion, VRX manufactures marijuana extracts. SVYZY's market cap is $12 billion and trades at $14 a share, producing Marinol for use in the treatment of excessive weight loss due to AIDS and anorexia nervosa. GWPH sells for $56 a share with a market cap of $931 million.

"Marijuana pharmaceuticals make up only a small part of their business, but these companies have been around for many years and while all three have large market caps, only VRX and SVYZY are generating earnings," said Fuld.

With all the fanfare of legalization, critics aren't convinced of the long term viability of the companies listed on the marijuana stock index.

"We've seen many sectors in the past with great promise like nanotechnology, ethanol, solar and homeland defense," Sykes told MainStreet. "They all lost their luster quicker than anyone expected."

--Written by Juliette Fairley for MainStreet