1 big risk to UK shares in 2021 and how I’d invest for great returns anyway Image source: Getty Images. 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… Our 6 ‘Best Buys Now’ Shares While going over updates for FTSE 100 and FTSE 250 shares earlier today, I found a curious trend. These UK shares are some of the biggest gainers. But their updates aren’t great.In fact, some of them are still quite weak. I’m talking about stocks like luxury giant Burberry, publisher Pearson, and retailer WH Smith. 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…So why are their prices rising? The big risk for UK sharesI think the combination of growing investor confidence and their changed assessment of company performance is the reason. So, the fact that these companies’ revenues are down, but less so than in their previous updates, is seen as positive. And there’s no doubt that progress is being made. But I think it’s important to remember that we are still living in a pandemic and it will be some time before we can truly claim victory over it. Until such time, there is still the risk of Covid-19 spreading, especially with new variants around. The longer the pandemic drags on, the worse it will be for business, making many companies and share prices increasingly vulnerable. How I’d buy UK shares nowDoes that mean we should refrain from buying the affected UK shares?I think there’s still much value to many of these stocks and they aren’t going under in a hurry. So the short answer is, no. At the same time, it’s important to keep in mind that these stocks aren’t exactly financially strong right now either. I’d buy some of them — in fact, I already have. Safer growth optionsBut I’d also hold shares with a high likelihood of growth and less risk. This will ensure that at least part of my portfolio is firmly on the growth path, even if the rest might struggle because of any untoward event. Some of the shares that did well during 2020, will continue to do this year, in my view. And there’s plenty of choice. FTSE 100 healthcare companies like AstraZeneca and Hikma Pharmaceuticals are examples. Support products and services providers like hygienist Rentokil Initial and face-mask and gloves distributor Bunzl are others. Ensuring some passive incomeI’d also ensure that there are income-generating UK shares in my portfolio. This will ensure passive income (as companies increasingly start paying dividends) at the very least, even if the overall market is indifferent. The catch though, is this. I want to buy UK shares with relatively stable dividends. The large-scale disruption last year led to dwindling in dividends across the board. Some companies were exceptions however, and I’d consider them as potential income investments. The FTSE 100 industrial metals miner Rio Tinto is an example of a stock that not just continued to pay dividends, it also paid an interim dividend. With a yield close to 5%, it’s definitely one to consider. National Grid, with an even better yield of 5.6%, is another one, as are other FTSE 100 utilities. See all posts by Manika Premsingh 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. Click here to get access to our presentation, and learn how to get the name of this ‘double agent’! Enter Your Email Address 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. Manika Premsingh owns shares of AstraZeneca and Rentokil Initial. The Motley Fool UK has recommended Hikma Pharmaceuticals. 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. Manika Premsingh | Wednesday, 20th January, 2021 There’s a ‘double agent’ hiding in the FTSE… we recommend you buy it! Simply click below to discover how you can take advantage of this.