Investors hoping for the chance to buy a piece of Aramco, Saudi Arabia’s state-owned oil behemoth, will probably have to wait.

Aramco had indicated that it expected to begin trading on a public stock market later this year, but, according to three people briefed on the company’s planning, that is now likely to happen in 2019. The delay reflects the difficulties in arranging what would easily be the world’s biggest-ever initial public offering.

The company’s potential market debut, a centerpiece of an ambitious economic overhaul of Saudi Arabia by Crown Prince Mohammed bin Salman, has drawn the interest of investors around the world — and political leaders hoping to win the listing.

In November, President Trump publicly courted Saudi officials to list Aramco on the New York Stock Exchange on Twitter. British government officials met with their Saudi counterparts during Crown Prince Mohammed’s visit to Britain last week. Shinzo Abe, the prime minister of Japan, has privately made entreaties for consideration of the Tokyo Stock Exchange as well.