The stock market has bounced off its lows from last year. However, shares of many excellent companies remain well below their peaks. Because of that, investors with some money to spare have lots of interesting opportunities these days. And that can make it hard to know which stocks to buy.

One smart investment strategy is to follow the insight of investing legend Peter Lynch. Among his pearls of wisdom is that "the best stock to buy is the one you already own." The implication is that it is often smarter to add to an existing position than to start a new one.

Two top options for dividend investors to consider adding to this month (or adding to their portfolio if they don't already own them) are Realty Income (O 1.94%) and STAG Industrial (STAG 1.60%). The shares of both real estate investment trusts (REITs) are down from their peak levels last year, which has pushed up their dividend yields. Because of that, a $500 (or any other amount) investment split between the two seems like a smart move this February.

Remarkable consistency

Shares of Realty Income have fallen about 10% from their peak level last year. Because of that and a steadily rising payout, the REIT now yields 4.4%, more than double the dividend yield of the S&P 500. That would allow an investor to add about $11 to their annual dividend income on a $250 investment. As a monthly dividend stock, Realty Income is great for those who use their dividend income to help cover expenses or to make new investments each month.

Realty Income pays one of the safest dividends in the REIT sector. The company built a rock-solid foundation anchored by a high-quality real estate portfolio and a top-tier balance sheet.

Realty Income owns over 11,700 retail, industrial, and other properties leased primarily to tenants resilient to economic downturns or the pressures of e-commerce. These include grocery stores, warehouses, convenience stores, and pharmacies. The company leases its properties to high-quality tenants under long-term net leases, making them responsible for maintenance, building insurance, and real estate taxes. That real estate portfolio produces very stable rental income to support its dividend.

Meanwhile, Realty Income pays out a conservative portion of its rental income via the dividend (76% of its adjusted funds from operations, or FFO, last quarter). That gives it a nice cushion and allows it to retain some money to fund acquisitions. And Realty Income's strong investment-grade balance sheet gives it further flexibility to expand its portfolio. That financial strength has enabled Realty Income to steadily grow its portfolio and dividend. The REIT has increased its payout for more than 100 straight quarters.

A rock-solid income stock

STAG Industrial's stock has shed a quarter of its value from early last year, helping push its dividend yield to 4.1%. Like Realty Income, STAG Industrial pays a monthly dividend, making it great for those seeking to earn recurring dividend income.

The industrial REIT also pays a rock-solid dividend. The company owns over 560 warehouses and light manufacturing properties that are operationally critical for tenants, supplying it with stable and growing rental income. Demand for industrial real estate has strengthened in recent years, driven by increasing e-commerce adoption and supply chain issues. That has enabled the company to secure much higher lease rates as existing agreements expire, as well as maintain high occupancy rates.

STAG Industrial generates enough rental income to cover its dividend with ample room to spare (its FFO payout ratio is below 80%), enabling it to retain some free cash flow to fund new investments. STAG complements that with a solid balance sheet, giving it lots of liquidity to finance its expansion. The company acquires operating properties and those it can invest in to add value and drive higher returns. These investments complement rent growth, enabling STAG Industrial to increase its dividend steadily.

A good time to add

Realty Income and STAG Industrial are excellent dividend stocks. They offer above-average-yielding monthly dividends, which have steadily increased over the years. With their stock prices down and more growth ahead, they look like smart dividend stocks to add to this month.