Unless you've been living under the proverbial investing rock, you'd probably be aware that American shares, particularly those in the NASDAQ-100 Index (NASDAQ: NDX), have enjoyed a stunning year in 2024. As it currently stands, the ASX's BetaShares Nasdaq 100 ETF (ASX: NDQ), which tracks the Nasdaq 100, is up more than 30% since January.

And that only accounts for share (or in this case, unit) price gains. The NDQ exchange-traded fund (ETF) has also paid out two dividend distributions to ASX investors this year. Accounting for those as well, our return from this index fund swells to over 32%

NDQ's long-term ASX investors are probably laughing all the way to the bank right now, given that this ETF has averaged a 21.22% return per annum over the past five years (as of 31 October anyway).

But past returns matter very little to investors who might be wondering whether it's too late to put money into this seemingly lucrative investment. So today, let's talk about what 2025 might hold in store for ASX owners of the NDQ ETF.

Can the NDQ ETF give ASX investors another 32% in 2025?

Right off the bat, if the BetaShares Nasdaq 100 ETF returns another 32% in 2025, it would be a seismic event.

For that to occur, we'd probably have to see the US$3.59 trillion market capitalisation of Apple swell to over US$4 trillion. Ditto with the US$3.36 trillion NVIDIA Corporation, which, mind you, is already up almost 190% over 2024 to date.

These two stocks are currently the largest holdings in the NDQ ETF and are partly to thank for this ETF's stunning 2024 performance.

We'd also probably need to see Microsoft, Amazon, Meta Platforms, Tesla, and Alphabet continue this year's momentum.

To be fair, most of these companies continue to grow their revenues and earnings at a healthy clip. However, some of the share price gains we have seen amongst the 'magnificent seven' in 2024 have come from an expansion of their price-to-earnings (P/E) ratios, meaning investors have become more willing to pay ever-increasing price tags for each dollar of earnings these stocks bring in.

To illustrate, Nvidia currently trades on a P/E ratio of 54.6. Apple is currently on 39.4, while Amazon is asking 45.16. Tesla takes the cake with its lofty 97.91 earnings multiple. Out of these seven stocks, only Google-owner Alphabet is currently on a P/E ratio of under 30. Some big numbers for multi-trillion-dollar companies, to be sure.

Foolish takeaway

If the NDQ ETF is to repeat its stellar 2024 performance, these ratios will likely need to keep rising. As history shows, that can only go on for so long.

History also tells us that anything is possible on the markets. So, it is entirely conceivable that the Betashares Nasdaq 100 ETF will enjoy another stunner in 2025. But I also wouldn't be surprised if we see NDQ experience a far tamer year on the ASX next year, given how explosive its recent performance has been. Only time will tell.