Rupert Hargreaves owns no share mentioned. The Motley Fool UK has recommended Just Eat Takeaway.com N.V. and Ocado Group. 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. 2 sliding FTSE 100 shares I’d buy See all posts by Rupert Hargreaves Click here to claim your copy now — and we’ll tell you the name of this Top US Share… free of charge! 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. 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Rupert Hargreaves | Tuesday, 18th May, 2021 | More on: JET OCDO 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. Our 6 ‘Best Buys Now’ Shares Enter Your Email Address Simply click below to discover how you can take advantage of this. The FTSE 100 has been sliding recently. However, I’d take this opportunity to snap up some high-growth shares at discounted valuations. Here are two companies I’m considering buying. FTSE 100 shares to buy One company that’s underperformed the market recently is Just Eat Takeaway.Com (LSE: JET). Year-to-date, the stock has underperformed the FTSE 100 index by around 34%, losing 28%, compared to the index’s 7% return. 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…Over the past 12 months, shares in Just Eat have lost 29%, compared to a 17% return for the FTSE 100, excluding dividends. I think this could be a fantastic opportunity to buy the growth stock. Its fundamental performance has dramatically improved over the past year. The company’s latest trading update announced it had processed 200m customer orders in the first quarter, an increase of 79% year-on-year. While the business has been given a helping hand by the pandemic, with consumers confined to their homes, management is still expecting order growth this year as the economy opens up.I’m inclined to believe this optimistic view. The pandemic has changed consumers’ behaviour, and it’s rapidly accelerated the adoption of technologies, such as online takeaway ordering. That said, the market is highly competitive. As a result, competition may restrict Just Eat’s ability to grow in the years ahead. The company is also spending a considerable amount on customer acquisition. This is holding back profitability. If spending continues at current levels, the group may have to raise more money from shareholders at some point in the future. Still, I’d buy the company for my portfolio of FTSE 100 shares today, despite these risks and challenges. Technology championThe other growth stock I’d buy after recent declines is Ocado (LSE: OCDO). Year-to-date, this stock has fallen in value by 17%. Over the past year, it’s returned just 3%. The pandemic has also given a significant boost to this company. It’s had to rapidly expand capacity in order to meet rising demand from customers. Retailers around the world have also realised the potential of having automated fulfilment centres.Ocado, which sells the technology to help retailers build automated fulfilment centres, should benefit from this. I think the company is a great way to invest in technology because the business is both a defensive supermarket retailer and a growing tech business. Still, this investment might not be suitable for all. Ocado is currently caught up in a legal battle over its technology, which could decimate its market position if it loses. Furthermore, like Just Eat, the business is also spending a lot of money to expand. This outlay could cause the company some issues in the future, especially if it struggles to raise additional financing. I will keep these challenges and risks in mind going forward. However, considering Ocado’s potential, I’d buy the stock after recent declines.