Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to add some large-cap growth stocks to your portfolio but don't have the time or expertise to hand-pick a few, the Vanguard Russell 1000 Growth Index ETF (VONG -1.38%) could save you a lot of trouble. Instead of trying to figure out which large-cap growth stocks will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual-fund cousins. This ETF, focused on large-cap growth stocks, sports a very low expense ratio -- an annual fee -- of 0.15%.

This ETF has slightly underperformed the S&P 500 over the past three years and doesn't yet have five full years under its belt. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

Why large-cap growth stocks?
Large-cap growth stocks can add some ballast to your collection. Many big companies may not grow as briskly as their smaller counterparts, but in order to reach their current size, they likely have some strong assets and features. Some can grow quite briskly, too, and this ETF focuses on such giants.

More than a handful of large-cap growth stocks had strong performances over the past year. Gilead Sciences (GILD -0.84%), up 98%, is waiting for FDA approval for its all-oral hepatitis C treatment, sofosbuvir, which has delivered strong results and received a favorable review from the FDA. The drug also seems headed for approval in Europe and, if approved, has a chance of outselling some competing formulas. Gilead is well-known for its success with HIV drugs,  and it just got European approval for an HIV treatment. The company is tackling non-Hodgkin lymphoma, too, while also addressing heart disease with its cardiovascular drugs Letairis and Ranexa.

Qualcomm (QCOM -2.19%), up 18%, is a top player in the smartphone world, supplying iDevices and Android units alike with its chips. The company's fourth-quarter report was mixed, with revenue up 33%, but earnings are up only 18%, which was below estimates. Qualcomm hiked its dividend by 40% earlier this year, and its yield is now at 1.9%. Its dividend has been growing by more than 20% annually in recent years. A bit of bad news is that Qualcomm's growth in China may be hampered by a Chinese probe into possible antimonopoly practices. Bulls like Qualcomm's expansion into health care and telemedicine, and the company is moving more strongly into networking as well.

Data management software giant Oracle (ORCL -1.73%), up 14% and yielding about 1.4%, isn't the fast grower it once was. It has made some competitive compromises and partnerships and is one of the companies involved in working to get the website fixed. One thing that hasn't changed is CEO Larry Ellison's generous compensation, which has often been in the tens of millions and in 2013 topped $150 million. Oracle is facing significant competition from other tech titans, as well as from relative upstarts such as Workday, which has struck a partnership with Oracle has doubled its dividend while announcing big stock buybacks and generating prodigious free cash flow that tops $14 billion annually. The stock seems appealingly valued at recent levels.

Other large-cap growth stocks didn't do quite so well over the last year, but we could see their fortunes change in years to come. Philip Morris International (PM -0.65%), for example, is about flat over the year and yields 4.3%. With domestic tobacco companies challenged by tightening regulations, rising taxes, and a shrinking smoking base, many have assumed that Philip Morris is the best bet in tobacco. But in the third quarter, it posted the weakest results, with volume taking a sizable drop and a strong dollar reducing its earnings. The company also raised the specter of lower volume and likely lower returns for investors. Philip Morris does have its fans, though, who like its innovation, its share buybacks, and its embrace of electronic cigarettes.

The big picture
If you're interested in adding some large-cap growth stocks to your portfolio, consider doing so via an ETF. A well-chosen ETF can grant you instant diversification across any industry or group of companies and make investing in it -- and profiting from it -- that much easier.