With the debt ceiling crisis behind us, the S&P 500 index has trended higher, rising 3.9% over the past month and entering into bull market territory. While worries about inflation and global growth remain, investors should be focused on positioning themselves for the next leg up by accumulating undervalued stocks. For those with a high risk tolerance, this might include a small allocation toward high-growth penny stocks.

Bullish sentiment in the market is often first reflected in blue-chip stocks. It then trickles down to growth stocks and penny stocks as investors become more confident. Therefore, some of the top penny stocks to buy still trade at attractive valuations.

Further, the names below are not speculative in the way most penny stocks are. They have solid fundamentals, with the potential for accelerated revenue growth and margin expansion.

Hecla Mining (HL)

First up on today’s list of high-potential penny stocks to buy is precious metals miner Hecla Mining (NYSE:HL). Currently priced around $5 a share, the stock has been trading sideways for the past six months. A breakout to the upside seems imminent considering the company’s growth outlook.

The company claims to be the largest silver producer in the United States. I am bullish on the outlook for gold and silver in the coming years and expect Hecla to benefit from higher precious metals prices, as well as production growth.

In 2022, Hecla’s silver production increased by 10%. Production growth is expected to accelerate to 18% in 2023 and to 35% by 2025. Thus, the next few years are likely to be strong from the perspective of EBITDA and cash flow upside.

In April, Hecla signed an agreement to acquire ATAC Resources (OTCMKTS:ATADF). The acquisition gives the company access to “significant land packages in highly prospective and tier one mining jurisdictions,” said President and Chief Executive Officer (CEO) Phillips S. Baker Jr.

As Hecla’s exploration base expands, robust growth is likely to sustain beyond 2025.

Bitfarms (BITF)

Trading at just over $1 a share, cryptocurrency miner Bitfarms (NASDAQ:BITF) could not only double in price over the next 12-24 months but perhaps even be a 5- or 10-bagger if Bitcoin (BTC-USD) soars to new heights.

In May, Bitfarms expanded its mining capacity by 47% on a year-over-year basis to 5 exahash per second (EH/s). The company expects further capacity expansion to 6 EH/s by the third quarter. Capacity expansion coupled with the rally in Bitcoin would translate into healthy revenue and EBITDA growth, as well as stellar free cash flows, for the low-cost Bitcoin miner.

The company’s growth trajectory is supported by a strong balance sheet. Bitfarms reported a liquidity buffer of $41 million as of Q1. Further, the company has reduced debt by $140 million in the past 10 months.

If Bitcoin continues to trend higher, I expect aggressive capacity expansion in 2024.

EVgo (EVGO)

Shares of EVgo (NASDAQ:EVGO), which operates a fast-charging network for electric vehicles (EVs), have declined by 56% in the past 12 months to less than $4. However, with EVGO poised for a reversal rally, it is one of the top penny stocks to buy at these beaten-down levels.

In the first quarter, revenue surged 229% year over year to $25.3 million. While growth has been stellar, EBITDA losses have kept the stock price depressed.

Having said that, I expect margin improvement with operating leverage and recurring revenue. As of Q1, the EV charging infrastructure company had around 3,100 stalls operational or under construction.

Revenue growth is likely to remain strong with management forecasting revenue in the range of $105 million to $150 million for the full year. At the midpoint of guidance, that would represent growth of more than 133%.

If EVgo can deliver revenue at the upper end of the guidance, it could be a strong upside catalyst for shares.

On the date of publication, Faisal Humayun did not hold (either directly or indirectly) any positions in the securities mentioned in this article. The opinions expressed in this article are those of the writer, subject to the InvestorPlace.com Publishing Guidelines.