Two of the world’s largest tobacco companies, Philip Morris International and the Altria Group, are discussing a merger that would reunite them after more than a decade in a deal aimed at domination of the fast-growing electronic-cigarette market.

Analysts and investors have long speculated that the companies would merge, given mounting pressure from declining cigarette sales and the need to invest in other sources of revenue.

The companies issued a statement disclosing the talks on Tuesday, which they described as an “all-stock, merger of equals.” A merger would create a company with a market value of more than $200 billion.

Industrywide cigarette sales volumes tumbled 4.5 percent on an adjusted basis in 2018, according to analysts at Cowen. In contrast, the e-cigarette market was worth about $11 billion in 2018 and is expected to grow at more than 8 percent annually over the next five years, according to the research firm Mordor Intelligence.