As online travel agency stocks Priceline (PCLN), Expedia (EXPE) and TripAdvisor (TRIP) slide amid the broader market weakness following the Brexit vote, Piper Jaffray analyst Michael Olson said the pullback is likely a buying opportunity for long-term investors. European travel is largely intra-country and intra-continent and while the U.K. represents a sizeable, near-7% of Europe's demand, this is not a "catastrophic" portion of Europe's travel business being potentially impacted, Olson tells investors. Noting as well that many believe the actual exit process will take at least two years, Olson believes this slow change will mitigate the most important factor in travel health, which he identifies as consumer sentiment. The firm keeps Overweight ratings on all three OTAs mentioned.