Robinhood investors like variety. You can find plenty of stocks on the trading platform's 100 most popular list with sky-high share prices. However, you can find some really cheap stocks, as well.

Currently, there are 13 stocks included in the 100 most widely held stocks on Robinhood that have share prices of less than $5 and therefore qualify as penny stocks. Here are the three most profitable penny stocks on Robinhood -- and whether or not any of them are good picks to buy right now.

Pennies next to a document with Penny Stocks printed on it and a magnifying glass on top of it.

Image source: Getty Images.

1. Ideanomics

Ideanomics (IDEX -1.00%) ranks as the most profitable Robinhood penny stock of all. That distinction comes with a caveat, though: The company actually isn't profitable. It posted a net loss of $737,000 in the first quarter of 2021. However, that relatively small loss is enough to land Ideanomics at the top spot on our list.

The company focuses on fintech and electric vehicles. Ideanomics Capital operates platforms for real estate, technology-related metals commodity trading, and trading for small stocks. Its mobility division helps customers transition to all-electric commercial fleets.

Although Ideanomics isn't generating profits yet, its bottom line is moving in the right direction, thanks to strong revenue growth. This improving financial performance has stemmed primarily from acquisitions. The company's title and escrow business Timios and inductive-charging business WAVE, both of which were acquired in the first quarter of 2021, together contributed nearly 90% of Ideanomics' total revenue in Q1. 

2. Zomedica

Zomedica (ZOM 0.42%) trails only Canadian cannabis-operator Sundial Growers among penny stocks on the top Robinhood stocks in July. And it's the second-most profitable (or to be more accurate, the second-least unprofitable) penny stock on the list, with a Q1 loss of $4 million.

The company markets point-of-care diagnostics products for veterinarians. Zomedica launched its first product Truforma earlier this year. It's a compact device that helps vets to diagnose adrenal and thyroid conditions in cats and dogs, with more tests planned.

Zomedica's main priority now is building up its sales and support team to advance the commercial launch of Truforma. It also expects to begin marketing two new tests for the diagnostics platform later this year.

3. Invesco Mortgage Capital

Invesco Mortgage Capital (IVR 0.36%) comes in third on the list of the "most profitable" Robinhood penny stocks. The company posted a net loss of $9.3 million in the first quarter of 2021, with a whopping $331.9 million loss on investments weighing on its bottom line.

The company is organized as a real estate investment trust (REIT). It focuses primarily on investing in commercial and residential mortgage-backed securities and other mortgage-related assets. 

Invesco Mortgage Capital is managed by Invesco Advisers, which is a wholly owned subsidiary of Invesco Ltd. The stock's main draw for investors is its dividend yield of more than 9.7%.

Are they buys?

There certainly are things to like about each of these stocks. Ideanomics has an intriguing business model with its goal to help companies electrify their fleets. Zomedica's Truforma platform holds the potential to make a big difference for veterinarians. Invesco Mortgage Capital's dividend yield is enough to make an income-seeking investor's mouth water.

However, my concern is that there are plenty of things to dislike about these stocks, as well. Near the top of the list is that none of these "most profitable" Robinhood penny stocks are generating a profit. Each company also faces significant risks of failure in achieving its goals.

Penny stocks usually aren't great picks for long-term investors. I don't see Ideanomics, Zomedica, or Invesco Mortgage Capital as exceptions to the rule right now. There are other stocks on the Robinhood top 100 list that offer much better risk-reward propositions.