There's no doubt that the S&P 500 is the most closely watched stock market index. The group of 500 or so large and profitable enterprises provides investors with a clear gauge of how stocks are performing. And it has been a popular investment choice historically.

In the past decade, the S&P 500 has generated a total return of 232%. That translates to an impressive 12.7% per year. However, there's one thriving exchange-traded fund (ETF) that has performed even better that investors should consider buying right now.

Unique market exposure

Investors need to get familiar with the Invesco QQQ Trust (NASDAQ: QQQ) . This ETF tracks the performance of the Nasdaq-100 i ndex , which consists of the 100 biggest non-financial businesses trading on the Nasdaq Composite.

The S&P 500 has solid exposure across various industries. But the QQQ is heavily skewed toward the technology sector. As of Aug. 9, 50% of the ETF's assets were represented by these types of businesses.

It shouldn't be a surprise that the " Magnificent Seven " reigns supreme. Combined, Alphabet , Amazon , Apple , Meta Platforms , Microsoft , Nvidia , and Tesla make up 42% of the entire fund. The better these stocks perform, the higher their weighting in the QQQ.

Given that these seven companies benefit from many secular tailwinds, like cloud computing, digital advertising, streaming entertainment, and electric vehicles, growth has been notable. And they all have exposure to the ongoing artificial intelligence (AI) boom in one form or another. This focus on disruptive and innovative businesses means that investors haven't had to identify single stocks that can outperform. While some might view this ETF as being riskier, owning it has proven to be a fruitful endeavor.

Stellar performance

Performance is perhaps the single most important variable that draws investors in. While the S&P 500 has done well in the last decade, it doesn't hold a candle to the Invesco QQQ Trust. The latter has put up a phenomenal total return of 412% since August 2014, which would've turned a $10,000 initial investment into more than $51,000 today. There's no question that this strong performance beats most active fund managers, too.

The tech sector shines brightly, but communication services and consumer-discretionary stocks are also well-represented. The strength of the economy for most of the past 10 years, bolstered by low interest rates and an accommodative Fed, have definitely helped.

The returns are hard to ignore, but investors will cheer when they find out that the QQQ charges a small expense ratio of 0.2%. Only $20 on every $10,000 in invested capital is directed toward paying the fee. That's a very small price to pay for such impressive performance.

Buy the dip

The Invesco QQQ Trust is taking a mid-summer breather, as it trades roughly 10% off its all-time record level from last month. A rotation out of tech stocks and soft economic data aren't helping the cause. Consequently, investors might be thinking that it's best to wait to buy until there's more clarity.

I view this as the wrong approach. Trying to correctly time the market is a losing proposition, and it can lead to more harm than good. It's more important, in my opinion, to invest early and often, particularly for those individuals who have a very long-term time horizon.

While I don't believe the QQQ will register the same types of gains that it has in the recent past, which have been exceptional, it still looks like a worthy investment option that has the potential to continue beating the S&P 500. The latest dip means it's a good time to buy.

Before you buy stock in Invesco QQQ Trust, consider this: