I bought some shares in Sep 2015 at 87 a share after it had fallen from the 2015 high of 120, then the stock headed down to end the year at 72, but climbed fairly steady from that point. Zachs currently rates it as #2 which is a buy rating for whatever that is worth. You will be cutting a fat hog while riding the backs of the employees with a total yearly dividend yield of 2.11% at its current price. With a P/E under 10 it is not valued too high but it seldom is that over valued. Bear in mind in the last 5 years the low was reached at 72 just after I bought the stock at 87. If UNP buys ahares that will reduce the shares on the public market which can help in the near term.
Holding my shares the stock proved to be a fairly good investment with little excitement. My lousy advice would be to decide how many shares you would like to own and buy some now, with more purchases when it drops again, plus reinvest the dividends. By reinvesting dividends you can calm yourself when it tanks by thinking, this is okay my divs are buying more shares now.