These companies have a strong presence in growing markets and shares trade at reasonable valuations. Those qualities could send both stocks higher in the long term. The S&P 500 (^GSPC 1.20%) just had its second-strongest first quarter in the past decade. The index advanced 10.2% during the three-month period that ended in March, notching 22 record highs along the way. Meanwhile, valuations across the stock market have become much more expensive, but buying opportunities still exist. For instance, Datadog (D ...