NEW YORK ( TheStreet) -- There are several investing codes by which I try to live. Aside from the fundamental principle of "buy low and sell high," I also never underestimate the value of a strong balance sheet, especially when it is filled with well diversified businesses.For this reason (among others) I never believed JPMorgan Chase ( JPM), which is still working to overcome a few embarrassments, was in any sort of prolonged danger. In fact, even with the bank's disappointing April quarter, which angered some analysts, in the company's defense I said the following: The results of this quarter notwithstanding, JPMorgan still has a strong business in investment banking, mortgages and retail banking. If the bank can continue to produce solid return on equity in the low-to-mid single-digits coupled with a discount rate of 9.5%, fair value on the stock can reach $55. Plus, given the potential for share buybacks over the next several quarters, along with an improving balance sheet, investors can still get a 20% premium just by being patient. I won't disagree that the now-infamous London Whale trade has knocked some shine off JPMorgan's armor. But in these situations Wall Street has always had a very short memory as long as companies apologize with higher revenue and profits. With the stock up 27% for the year to date and trading at around $55 per share, it's safe to say that all is forgiven. With the bank now producing fee income growth of more than 30%, there's no question that when compared to Bank of America ( BAC) and Citigroup ( C), shares of JPMorgan are still undervalued. What's more, there are very few banks that can match JPMorgan's performance in terms of profitability and credit quality. I'm not suggesting the bank has fully recovered from recent operational deficits. But the recent 13% revenue growth and the better-than-expected performance from its trading business suggest that some of the bigger problems are now in the rear-view mirror. WFC) as well as several smaller regional banks such as BB&T ( BBT).