Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to add exposure to the Russell 1000 index of large-cap stocks to your portfolio, the SPDR Russell 1000 ETF (NYSEMKT:ONEK) could save you a lot of trouble. Instead of trying to figure out which stocks will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios (annual fees) than their mutual fund cousins. This ETF, which tracks the Russell 1000, sports a very low expense ratio of 0.1%. The fund is small, though, so if you're thinking of buying, beware of possibly large spreads between its bid and ask prices. Consider using a limit order if you want to buy in. It recently yielded about 1.8%. 

This Russell 1000 ETF has slightly lagged the S&P 500 over the past three and five years. 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 the Russell 1000?
If you're interested in owning most of the market in a simple and inexpensive way, the Russell 1000-focused ETF will do it. It includes about 1,000 of the largest companies in the even bigger Russell 3000 index. The Russell 3000 reflects nearly the entire U.S. market, while the Russell 1000 represents a respectable 92%.

More than a handful of Russell 1000 companies had strong performances over the past year. Data management software giant Oracle (NYSE:ORCL), for example, popped 26.5%, and it yields about 1.2% after some aggressive dividend increases. Its free cash flow tops $14 billion annually, and it has been using some of that for acquisitions, such as online marketing specialist Responsys and cloud-computing player Corente. Oracle faces significant competition from other tech titans, as well as relative upstarts, but it's still performing well. In 2013, Oracle overtook IBM (NYSE:IBM) as the world's second-largest software company.

Qualcomm (NASDAQ:QCOM), the leading mobile-chip maker, jumped 23% over the past year. Its new Snapdragon 805 chip has been well received, and Qualcomm is poised to profit from China, too (though it also faces some regulatory challenges there). The company has been growing in the health care and networking  arenas as well. It faces strong competition on various fronts, but it's worth remembering that Qualcomm gets most of its revenue by licensing technology, not chip sales. Qualcomm has been hiking its dividend aggressively for a decade now, and its yield is at 1.8%.

General Electric (NYSE:GE) gained 17.2% and yields 3.4%. It has been transforming itself lately, becoming much more of an energy company -- its oil and gas segment is now its fourth-largest revenue-generator. GE is more of a manufacturing company as well, which enables it to collect more revenue from services that support its products, such as maintenance contracts and repairs. Part of General Electric's transformation involves spinning off its sizable retail finance business. It does carry considerable debt, but that's manageable, as the company generates more than $15 billion in annual free cash flow. In recent news, GE is selling wind turbines to India, a rather large market.

Other Russell 1000 companies didn't do quite so well over the last year but could see their fortunes change in the coming years. IBM, for example, shed 6.5%, and its revenue and free cash flow have recently been below levels of a few years ago. Still, IBM's earnings and profit margins have been growing, and the company has been transforming itself from a hardware titan into a significant player in cloud computing and business analytics, which can deliver higher profit margins. The company isn't firing on all cylinders now, and it faces strong competition, but it has deep pockets and much potential, and it has been investing in future growth. For patient believers, IBM shares offer a dividend yield of about 2%, and with a forward P/E ratio below 10, its stock is appealing.

The big picture
If you're interested in adding Russell 1000 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 and profiting from it that much easier.