TGEN vs PESI

For growth investors, Tecogen Inc.

(TGEN) is the stronger pick with 19. 7% revenue growth year-over-year, versus 4. 3% for Perma-Fix Environmental Services, Inc. (PESI). Analysts rate Tecogen Inc. (TGEN) a "Buy" — based on 4 analyst ratings — the highest consensus in this comparison. The "better buy" depends entirely on your goals: growth investors should weight revenue trajectory, value investors should weight P/E and PEG, and income investors should weight dividend yield and streak.

Over the past 5 years, Tecogen Inc.

(TGEN) delivered a total return of +214. 7%, compared to +62. 7% for Perma-Fix Environmental Services, Inc. (PESI). Over 10 years, the gap is even starker: PESI returned +200. 4% versus TGEN's +7. 4%. Past returns do not guarantee future results, and the stock with the higher historical return may already have its best growth priced in.

By beta (market sensitivity over 5 years), Perma-Fix Environmental Services, Inc.

(PESI) is the lower-risk stock at 1. 85β versus Tecogen Inc. 's 3. 43β — meaning TGEN is approximately 86% more volatile than PESI relative to the S&P 500. On balance sheet safety, Perma-Fix Environmental Services, Inc. (PESI) carries a lower debt/equity ratio of 9% versus 13% for Tecogen Inc. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), Tecogen Inc.

(TGEN) is pulling ahead at 19. 7% versus 4. 3% for Perma-Fix Environmental Services, Inc. (PESI). On earnings-per-share growth, the picture is similar: Perma-Fix Environmental Services, Inc. grew EPS 43. 6% year-over-year, compared to -57. 9% for Tecogen Inc.. Over a 3-year CAGR, TGEN leads at 2. 7% annualised revenue growth. Higher growth typically commands a higher valuation multiple — check whether the premium P/E or P/S is justified by the growth rate using the PEG ratio.

Perma-Fix Environmental Services, Inc.

(PESI) is the more profitable company, earning -22. 3% net margin versus -30. 5% for Tecogen Inc. — meaning it keeps -22. 3% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: PESI leads at -19. 0% versus -26. 3% for TGEN. At the gross margin level — before operating expenses — TGEN leads at 36. 3%, reflecting greater pricing power or product mix advantage. Stronger margins indicate durable pricing power, lower cost of revenue, or higher mix of software/services. They are one of the clearest signs of business quality.

None of the stocks in this comparison currently pay a material dividend.

All are effectively zero-yield and should be held for capital appreciation rather than income.

For long-horizon retirement investors, Perma-Fix Environmental Services, Inc.

(PESI) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (+200. 4% 10Y return). Tecogen Inc. (TGEN) carries a higher beta of 3. 43 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (PESI: +200. 4%, TGEN: +7. 4%), confirming both are viable long-term holds — but the lower-volatility option typically results in less emotional selling during corrections. Retirement portfolios generally favour predictability over maximum returns. Consult a financial advisor before making allocation decisions.

Both stocks operate in the Industrials sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

In terms of investment character: TGEN is a small-cap high-growth stock; PESI is a small-cap quality compounder stock. These fundamental differences mean investors should not choose between them on a single metric — the "better stock" depends entirely on which of these characteristics aligns with your investment strategy.