Image source: Getty Images Pershing Square Holdings (LSE: PSH), run by billionaire hedge fund manager Bill Ackman, has been promoted to the FTSE 100. It will take its place among the UK’s blue-chip elite on 21 December.Despite outperforming the market by a wide margin over the last couple of years, PSH continues to trade at a substantial discount to its net asset value (NAV). This suggests it could offer a wide margin of safety and significant upside potential. But should I buy?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…Pershing Square dealLet me start by nailing down some numbers. PSH’s NAV per share at the end of last year was 2,035p. It’s increased 61% to 3,268p as of 30 November. Meanwhile, the share price has gone from 1,454p to a current 2,485p — a rise of 71%.As such, the discount of the shares to NAV (24%) has narrowed somewhat since the start of the year (29%). Nevertheless, if you’re buying the stock today, you’re paying just 76p for every £1 of PSH’s assets. On the face of it, this is a terrific deal. Particularly as the company has delivered a storming performance in a year of extraordinary turmoil.Attractive qualitiesListed in London in 2017, Pershing Square invests principally in publicly traded US-domiciled companies. Ackman looks to take a significant minority interest in a relatively small number of “superb businesses” when they’re trading at a discount to their “intrinsic value.” And he aims to be “an influential and supportive owner.”Ackman’s business-focused philosophy and concentrated portfolio chime with other investors I admire, like Warren Buffett, Terry Smith and Nick Train. On this basis, I think Pershing has inherently attractive qualities.As last reported, it owns stakes in 10 companies, including Starbucks, Burger King-owner Restaurant Brands, hospitality group Hilton, and key players in the US mortgage market, Fannie Mae and Freddie Mac.At this point you may be thinking: Hang on Henry, if PSH owns stocks like these, how on earth has it managed to produce such impressive returns? This is where things get a bit Twilight Zone-ish.Pershing Square, but part Bermuda TriangleAckman does some weird stuff most private investors don’t get involved in. He’s a hedge fund manager, after all!As my Motley Fool colleague Edward Sheldon explained in a recent article, Ackman turned $17m into $2.6bn from a bet against corporate debt earlier this year, just as the pandemic was unfolding. He then ploughed the proceeds into stocks, just as they began their big, post-crash rebound.Ackman’s wizardry can produce some outsized returns, almost from nowhere. But assets can also disappear when his bets go wrong. He had a run of losses a few years ago from some bad calls, including a massive short position against nutritional supplements seller Herbalife.Should I buy Pershing Square shares?I like Ackman’s core philosophy of investing in superb businesses when they’re trading at a discount to their intrinsic value. And Pershing Square offers UK investors a one-stop shop to buy into a small, actively-managed portfolio of such businesses listed in the US.But you also have to be aware that Ackman will make some big, idiosyncratic and often contrarian bets. I don’t see anything wrong with this per se. Not if you’re looking for a higher risk-higher reward investment. PSH certainly looks very buyable to me right now at its 24% discount to NAV. G A Chester | Friday, 4th December, 2020 | More on: PSH Enter Your Email Address “This Stock Could Be Like Buying Amazon in 1997” See all posts by G A Chester Click here to claim your copy now — and we’ll tell you the name of this Top US Share… free of charge! Our 6 ‘Best Buys Now’ Shares 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. 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. Bill Ackman’s Pershing Square is promoted to the FTSE 100. Should I buy? 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. G A Chester has no position in any of the shares mentioned. The Motley Fool UK owns shares of and has recommended Starbucks and recommends the following options: short January 2021 $100 calls on Starbucks and short January 2021 $100 calls on Starbucks. 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.