Just in time for the new year! Shark Tank star Kevin O'Leary is increasingly bullish on small-cap U.S. stocks as prospects for tax reform brighten.

O'Leary, who is Chairman of O'Shares ETF Investments, has an ETF that tracks some of the higher quality small-cap U.S. stocks, called the O'Shares FTSE Russell US Small Cap Quality Dividend ETF (OUSM) . The fund has returned 6.3% since the start of the year. 

Meanwhile, as for Tesla (TSLA) , O'Leary said the company is trading at a "stupid multiple."

"At some point, I don't know when, you're going to wake up as an investor and say this company walks like a duck, quacks like a duck and must be a duck - in other words, it's a car company," O'Leary said. "It has the same problems car companies have."

O'Leary wonders when the company will start to be valued as a car company.

"When does it turn into a car company and then be valued at the same multiples as a BMW, a Ford (F) , Toyota Motor (TM) , Hyundai, Kia?" he asked. "That day is going to be extremely painful for shareholders. That's when you see the stock go from the $300s to under $100."

Follow @ScottGamm on Twiter.

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