The market has rebounded impressively after a rough few months at the start of the year. Over the last three months, through July 29, the S&P 500 index has gained 14.6%.

However, Coca-Cola's (KO 1.42%) share price has moved in the opposite direction, losing 4.1%. That may scare some people, but dividend-seeking investors should view this as a buying opportunity.

In fact, Coca-Cola should be part of their core long-term holdings.

Image source: Getty Images.

Higher revenue

Coca-Cola only sells beverages. That means management can concentrate its efforts solely on this business and not get distracted by unrelated or tangential businesses. While it's known for soda, it also sells other drinks like water, juice, sports drinks, and plant-based beverages. That's beneficial given consumers' changing tastes. Right now, people have been more drawn to healthier drinks.

The company sells its products globally in more than 200 countries. This geographic reach helps diversify Coca-Cola's revenue stream.

Nonetheless, investors were undoubtedly disappointed by Coca-Cola's second-quarter revenue. While volume had been positive, it dropped in the second quarter.

Revenue, removing foreign-currency translation effects and the impact from acquisitions/divestitures, grew 5% from a year ago. This was entirely due to higher prices and a different mix, which added 6 percentage points. Decreased volume subtracted 1 percentage point.

Still, it's heartening to see Coca-Cola grow profits even in a challenging quarter. Adjusted operating income increased 15% year over year.

While consumers may have gotten tired of overall price increases, when they adjust, they'll undoubtedly buy more Coca-Cola products. They're popular and ubiquitous -- you can find the items in stores, restaurants, and stadiums, among other places.

Dividend grower

Fortunately, Coca-Cola investors can rely on collecting dividends. You can see the company's strong commitment by looking at its history. The board of directors raised the quarterly payout by more than 5% this year to $0.51. That marked an impressive 63 straight years of higher dividends, and makes the company a Dividend King.

Even more importantly, Coca-Cola has the ability to keep making payouts. It has a 69% payout ratio, which indicates the company can easily afford to keep paying dividends out of its earnings.

The stock has a higher dividend yield than the large-cap stocks as measured by the S&P 500. Coca-Cola shares yield 3% compared to 1.2% for the index.

Better valuation

Meanwhile, the share price drop over the last three months has resulted in a better valuation. Coca-Cola's price-to-earnings (P/E) ratio currently stands at 24, down from 29.

The stock also has a better valuation than the S&P 500. The index has a P/E multiple of 30.

Formed in 1886, Coca-Cola is a mature company, so it may never achieve breakneck sales and earnings growth. Its own long-term goals call for 4% to 6% annual revenue growth and 7% to 9% earnings per share increases.

But if you're looking for steady gains that produce stock price appreciation and dividends, Coca-Cola belongs in your portfolio. And with the recent stock price dip, the shares trade at a more attractive valuation.

That adds up to a buying opportunity for long-term investors looking for an attractive total return opportunity.