Edward Sheldon, CFA | Monday, 1st February, 2021 | More on: RR The Rolls-Royce share price has fallen again. Should I buy the stock now? Get the full details on this £5 stock now – while your report is free. For a brief period in late 2020, Rolls-Royce (LSE: RR) shares looked like they could be set to stage an amazing recovery. Between the start of October and early December, the RR share price rallied from 40p to 135p. Recently, however, the stock has lost its momentum again. Since its December high it’s fallen about 30%, while over a 12-month period it’s decreased by over 59%.Here, I’m going to look at what has caused the share price to dip. I’m also going to look at whether the stock is a good fit for my portfolio.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…Rolls-Royce: share price weaknessOne of the main reasons the Rolls-Royce share price has fallen recently is that it’s become clear the airline industry is going to continue facing near-term challenges. This is likely to impact Rolls-Royce. That’s because it generates a substantial proportion of its revenues from the manufacturing and servicing of aero engines for the commercial aviation industry. Much of its income is linked to flying hours.Back in November, when we got the news about the coronavirus vaccines, airline bookings immediately picked up. At the time, it looked like the outlook for the airline industry could improve substantially in the near term.However, this year, that outlook has deteriorated again due to the new strains of the coronavirus and the new travel/quarantine restrictions governments have introduced. Worryingly, the International Air Transport Association (IATA) recently warned that the situation may get worse before it gets better.Another reason the share price has dropped is that the company recently posted a rather disappointing trading update. Here, the company told investors it was expecting negative free cash flow of around £2bn in 2021. It also said 2021 widebody engine flying hours are expected to be around 55% of 2019 levels.I’ll point out, however, it wasn’t all bad news. The company did say it expects to turn cash flow positive at some point during the second half of 2021. It also said that, with liquidity of approximately £9bn, it’s confident of overcoming those challenging near-term market conditions and is “well-positioned for the future.” This is certainly encouraging.Should I buy RR shares?At some stage in the not-too-distant future, I expect the prospects for the airline industry and Rolls-Royce to improve. Whether it’s later this year, or in 2022, I think air travel will pick up. This should benefit Roll-Royce. It could result in the share price moving higher.That said, RR isn’t a stock I’d personally invest in today. As I explained recently, I like to invest in high-quality businesses that I believe have strong long-term growth prospects. I look for companies that are very profitable. That means producing a high return on capital employed, are financially sound and can demonstrate consistent top-line and bottom-line growth. This strategy suits my financial goals and risk tolerance. Rolls-Royce, unfortunately, doesn’t meet my investment criteria. Looking at the company’s financials, its track record when it comes to profitability isn’t great. In recent years, it’s posted big losses on a number of occasions. This is a concern for me.As I said, Rolls-Royce’s prospects could improve in the coming years. However, all things considered, I think there are other stocks I could buy right now that better fit my personal investment style. Enter Your Email Address Image source: Getty Images. 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More information about how The Fool collects, stores, and handles personal data is available in its Privacy Statement. 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. FREE REPORT: Why this £5 stock could be set to surge Our 6 ‘Best Buys Now’ Shares Simply click below to discover how you can take advantage of this. Edward Sheldon has no position in any 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.