Don’t miss our special stock presentation.It contains details of a UK-listed company our Motley Fool UK analysts are extremely enthusiastic about.They think it’s offering an incredible opportunity to grow your wealth over the long term – at its current price – regardless of what happens in the wider market.That’s why they’re referring to it as the FTSE’s ‘double agent’.Because they believe it’s working both with the market… And against it.To find out why we think you should add it to your portfolio today… Click here to get access to our presentation, and learn how to get the name of this ‘double agent’! With a Tier 4 having been introduced in parts of England this Christmas, it’s clear the fallout from the pandemic is very far from over. There’s also the real possibility that despite the action governments around the world have taken to try and prop up economies through this, the stock market could fall again.If that happens there are some defensive shares – those where demand remains even if the economy slumps – which should do better than most and keep paying dividends.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…The energy sector is well placed to survive any stock market fallTwo companies I’d back in the energy sector are SSE and National Grid. The former is particularly well placed to benefit from the transition to renewables. SSE is very focused on wind power in the UK and Ireland.National Grid could also benefit from exposure to renewables. In 2019 it bought Geronimo Energy in the US – a wind and solar developer in North America. I like National Grid’s US operations as well as its non-regulated activities that could both create platforms for future growth.Supermarkets: another sector for stable returnsDemand for food holds up in all economic conditions. As a market leader, I back Tesco to keep performing well, even as the discounters keep growing in the UK. It’s become a stronger business in recent years and is now under new leadership. Ken Murphy joined just a few months ago, a former Walgreens Boots Alliance executive.Tesco has become leaner and more focused on the UK. As such, I’d expect it to be able to provide steady, growing returns in the coming years and remain a strong business.Technology is here to stayTechnology has been the big winner of 2020. As millions worked from home and shopped online regularly, the transition to a digital world took leaps forward. It was a process that was already happening. This is good news for shares such as Softcat and FDM Group.The former is a technology reseller with an enviable record. I’ve liked the business for a while and expect it to keep doing well. Indeed, its performance this year shows why it’s a business that might be worth backing.In its full-year results, back in the summer, sales in the 12 months to 31 July were ahead 8.6% at £1.08bn. Operating profits meanwhile rose 10.9% to £93.7m. Earnings per share were 38.2p, a 10.4% increase.FDM Group, which is involved in IT training and IT support to businesses is also in a sweet spot for growth in a digital world.These are five shares that I expect can do well if the stock market falls again. All are very good businesses in my opinion. I think they will grow their share prices and dividends from this point on and reward investors. See all posts by Andy Ross Image source: Getty Images 5 UK shares I’d buy in my ISA if stock markets fall again 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. Andy Ross | Thursday, 24th December, 2020 Our 6 ‘Best Buys Now’ Shares Simply click below to discover how you can take advantage of this. Enter Your Email Address There’s a ‘double agent’ hiding in the FTSE… we recommend you buy it! 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. Andy Ross owns shares in National Grid. The Motley Fool UK has recommended Softcat and Tesco. 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.