1 safe-and-steady stock to research further and 2 we find risky

Stability is great, but low-volatility stocks may struggle to deliver market-beating returns over time as they sometimes underperform during bull markets.

Choosing the wrong investments can cause you to fall behind, which is why we started StockStory - to separate the winners from the losers. That said, here is one low-volatility stock that could succeed under all market conditions and two stuck in limbo.

Two stocks to sell:

Voya Financial (VOYA)

Rolling one-year beta: 0.58

Originally spun off from Dutch financial giant ING in 2013 and rebranded with a name suggesting "voyage," Voya Financial (NYSE:VOYA) provides workplace benefits and savings solutions to U.S. employers, helping their employees achieve better financial outcomes through retirement plans and insurance products.

Why Do We Think VOYA Will Underperform?

1. Muted 4.4% annual revenue growth over the last two years shows its demand lagged behind its financials peers

2. Incremental sales over the last two years were less profitable as its earnings per share were flat while its revenue grew

Voya Financial's stock price of $98.48 implies a valuation ratio of 9.2x forward P/E. Read our free research report to see why you should think twice about including VOYA in your portfolio, it's free .

TFS Financial (TFSL)

Rolling one-year beta: 0.02

Tracing its roots back to 1938 during the Great Depression era when savings and loans were vital to homeownership, TFS Financial (NASDAQ:TFSL) is a savings and loan holding company that provides mortgage lending, deposit services, and other retail banking products primarily in Ohio and Florida.

Why Are We Bearish on TFSL?

1. Muted 6.8% annual net interest income growth over the last five years shows its demand lagged behind its banking peers

2. Net interest margin of 1.8% is well below other banks, signaling its loans aren't very profitable

3. Capital generation will likely be weak over the next 12 months as Wall Street expects flat tangible book value per share

At $16.76 per share, TFS Financial trades at 2.4x forward P/B. Check out our free in-depth research report to learn more about why TFSL doesn't pass our bar .

One stock to watch:

UnitedHealth (UNH)

Rolling one-year beta: 0.73

With over 100 million people served across its various businesses and a workforce of more than 400,000, UnitedHealth Group (NYSE:UNH) operates a health insurance business and Optum, a healthcare services division that provides everything from pharmacy benefits to primary care.

Why Do We Like UNH?

1. 10% annual revenue growth over the last five years was better than the sector average, highlighting the value of its products and services

2. Dominant market position is represented by its $449.7 billion in revenue, which gives it negotiating power over membership pricing and reimbursement rates

3. ROIC punches in at 19.1%, illustrating management's expertise in identifying profitable investments