Is American Express (AXP) a buy?

Hello everyone! I have recently been looking into AXP stock as I believe it is undervalued right now. Here are a few numbers: **P/S:** 2.75 **P/E:** 19.77 **Forward P/E:** 16.03 **Earnings Growth 1 Year:** 14.20% **Earnings Growth 5 Year:** 14.28% **PEG:** 1.12 **P/FCF:** 13.75 **P/C:** 4.62 **Debt/Equity:** 1.73 **Dividend Yield:** 1.06% **Payout:** 21.33% I also used my own DCF valuation model and it resulted in an intrinsic value per share of $392.41 which suggests around 22% upside. This seems to me like a classic example of a great business at a fair price. It is also significantly cheaper than Visa or Mastercard. The upside is somewhat limited but I think the size and stability of the business more than make up for it. It is also the 2nd largest holding at Berkshire Hathaway! Let me know what you guys think on this one.