I would like to receive emails from you about product information and offers from The Fool and its business partners. Each of these emails will provide a link to unsubscribe from future emails. More information about how The Fool collects, stores, and handles personal data is available in its Privacy Statement. After declining by around 8% since the start of the year, the FTSE 100 now trades at its lowest level since January 2019. The speed of its fall in recent days is likely to have caught many investors by surprise. However, its declines have often been faster than its gains in bygone years.Looking ahead, further falls would be unsurprising in the short run. However, history shows that such periods can prove to be buying opportunities for long-term investors.5G is here – and shares of this ‘sleeping giant’ could be a great way for you to potentially profit!According to one leading industry firm, the 5G boom could create a global industry worth US$12.3 TRILLION out of thin air…And if you click here we’ll show you something that could be key to unlocking 5G’s full potential…Potential challengesThe full scale of the impact of coronavirus on the world economy is still a ‘known unknown’. Its impact on company earnings is gradually becoming clearer, with weak consumer demand in China and the restricted supply of a variety of products from the world’s second-largest economy causing many businesses to report a slowdown in sales.This situation could continue for as long as coronavirus remains a threat to the world economy. Investors may continue to price-in a global economic slowdown – especially since the upcoming US election may add an extra layer of concern to the views of many investors.Buying opportunityBuying shares right now may seem like an unwise move. After all, they could easily fall further in the short run if the coronavirus outbreak fails to be contained.However, a number of companies now appear to trade on low valuations given their long-term growth potential. Certainly, they may become even cheaper in the near term. But their risk/reward ratios seem to be favourable, and in many cases, investors may have factored-in further challenges for the world economy.Previous stock market crashes have caused significant pain and worry for investors in the short run. The global financial crisis, for example, caused the FTSE 100 to halve in value. However, it recovered in subsequent years – just as it has done following every other period of decline in the past. As such, investors who can identify high-quality companies and buy them at relatively low valuations may be handsomely rewarded in the long run.A fixed strategyOne of the challenges in buying shares during a market crash is overcoming your emotions. It is natural to feel fearful about the potential for losses due to the risks facing the wider economy.However, by having a fixed strategy in place that focuses on the long term, diversifies across a number of stocks, and sticks with the concept that buying undervalued shares has historically yielded high returns, you can overcome the inertia that often results from a market crash.In doing so, you may find that in a few years’ time, your portfolio valuation is relatively healthy and the current downturn in the stock market’s performance proves to be a temporary drop in its long-term growth towards new record highs. I’m sure you’ll agree that’s quite the statement from Motley Fool Co-Founder Tom Gardner.But since our US analyst team first recommended shares in this unique tech stock back in 2016, the value has soared.What’s more, we firmly believe there’s still plenty of upside in its future. In fact, even throughout the current coronavirus crisis, its performance has been beating Wall St expectations.And right now, we’re giving you a chance to discover exactly what has got our analysts all fired up about this niche industry phenomenon, in our FREE special report, A Top US Share From The Motley Fool. See all posts by Peter Stephens Enter Your Email Address Peter Stephens | Friday, 28th February, 2020 | More on: ^FTSE Peter Stephens has no position in any of the shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors. Our 6 ‘Best Buys Now’ Shares Simply click below to discover how you can take advantage of this. Renowned stock-picker Mark Rogers and his analyst team at The Motley Fool UK have named 6 shares that they believe UK investors should consider buying NOW.So if you’re looking for more stock ideas to try and best position your portfolio today, then it might be a good day for you. Because we’re offering a full 33% off your first year of membership to our flagship share-tipping service, backed by our ‘no quibbles’ 30-day subscription fee refund guarantee. Click here to claim your copy now — and we’ll tell you the name of this Top US Share… free of charge! The FTSE 100 is at its lowest level in a year. Here’s what I’d do now “This Stock Could Be Like Buying Amazon in 1997” Image source: Getty Images.