With 2025 fast approaching, I can't help but look back on 2024 and the three S&P/ASX 200 Index (ASX: XJO) stocks I opted not to buy at market open on 2 January, but wish I had.

So, with 20/20 hindsight vision and only five full trading days left in 'the old year', here are the three outperforming companies that would have supercharged my returns if I had taken the leap.

Three ASX 200 stocks that smashed the benchmark in 2024

The first ASX 200 stock I should have snapped up at the beginning of 2024 is Technology One Ltd (ASX: TNE).

On 2 January, shares in the software company were trading for $15.33. At the market close yesterday, those same shares were changing hands for $30.22, up 97.1%.

And that's not including the 22.5 cents a share in partly franked dividends Technology One paid out over the year. If we add those back in, then the accumulated value of Technology One shares has gained more than 98% year to date.

Which brings us to the second ASX 200 stock I wish I'd taken the plunge on at the start of this year: Pro Medicus Ltd (ASX: PME).

Shares in the health imaging company started 2024 trading at $96.30 each. Yesterday, the Pro Medicus share price closed the day at $250.23, up 159.8%.

Pro Medicus also paid 40 cents a share in fully franked dividends over the year, which would have nudged my accumulated gains from this missed investment opportunity to just over 160%.

Rounding out the list of ASX 200 stocks that I wish I'd bought and held throughout 2024 but did not, is Zip Co Ltd (ASX: ZIP).

On 2 January, I could have bought shares in the buy now, pay later (BNPL) stock for 62 cents apiece. Yesterday, Zip shares closed trading for $2.84, up a whopping 358%. As Zip doesn't pay dividends (yet), that would be the sum total of my gains.

But you wouldn't hear me complaining about Zip's performance!

Now, in the interest of some diversity, let's say I'd invested $5,000 in each of these ASX 200 stocks.

That would see me holding a technology stock, a healthcare stock, and a financial payments stock.

At yesterday's close, these three companies would have returned an average of 205.3% since market close on 2 January.

Or enough to turn my $15,000 investment on the day into $45,795 today.

Of course, that's all water under the potential gains bridge now.

With all eyes on 2025, the big question ASX 200 investors are facing today is which three companies will lead the pack higher in the new year.

I'll be back in that new year with some forecasts on this front for you.

Until then, wishing you happy holidays and prosperous investing.