Image credit: iStock/Thinkstock.

If you were to look at Bank of America (BAC 3.35%) and Citigroup's (C 1.41%) stocks on Monday, down an average of 5%, you'd think they had done something wrong. But the reality is that things are only getting better at the nation's second and fourth biggest banks, respectively.

To be fair, Bank of America and Citigroup aren't the only bank stocks that are down sharply today. The S&P 500 is off by nearly 2%, and bank stocks across the board are suffering, as fears of a potential recession have gripped the market. The fact that nothing is out of sorts at these two banks in particular should be clear when you look at the performance of all four of the nation's biggest banks:

Bank

Share Price on Monday, Feb. 8, 2015

JPMorgan Chase (JPM 2.51%)

(3.5%)

Bank of America

(5.5%)

Wells Fargo (WFC 2.74%)

(2%)

Citigroup

(4.4%)

Source: Yahoo! Finance (as of 11:30 EST).

What's important to note here is that there is little difference between the way the market is treating JPMorgan Chase and Wells Fargo, two of the nation's best-run banks, and the way it's treating Bank of America and Citigroup, two banks that have struggled over the past decade. And the difference that does exist is largely explained by the fact that Bank of America and Citigroup's shares are innately more volatile than JPMorgan Chase and Wells Fargo's. This is captured by their respective betas, which measures how much a specific stock moves relative to the market on an average day.

Bank

Beta

JPMorgan Chase

1.64

Bank of America

1.77

Wells Fargo

0.92

Citigroup

2.03

Source: Finviz.com.

You can see how this works by comparing Bank of America to Wells Fargo. Bank of America's beta of 1.77, means that it's 77% more volatile on average than the broader market. So if the S&P 500 is down by say 2% on any given day, Bank of America's shares will be down by 3.54%. Conversely, because Wells Fargo's beta is only 0.92, or less than 1.0, this means that its shares are 8% less volatile than the broader market on a typical day.

Differences in beta speak to a stock's speculative nature. Because of Wells Fargo and JPMorgan Chase's impressive performances during the financial crisis, investors perceive them to be safer and less speculative than Bank of America and Citigroup, both of which barely survived the 2008-09 downturn.

This goes to Warren Buffett's point that companies get the shareholders they deserve. Boring companies that make great long-term investments get long-term shareholders who don't trade in and out of their stocks. Meanwhile, less prudent companies get shareholders who are looking to make a quick buck by rapidly buying and selling their shares. This is evidenced by the average daily trading volumes of these four banks' stocks:


Data source: YCharts.com.

These differences aside, the important thing for investors to take note of right now is that both Bank of America and Citigroup are making impressive strides at returning to respectable profitability. Bank of America had its best year in nearly a decade in 2015. And Citigroup's earnings more than doubled last year compared to 2014.

These recoveries could slow down if a recession does indeed materialize, but I'd be surprised if the progress at these two banks stopped altogether. It's for this reason that I don't believe investors in either of these stocks should allow fear to influence their decisions about buying or selling shares of Bank of America or Citigroup in any way.