Shares of Saudi Tadawul Group, the owner of the kingdom’s $2.5 trillion dollar bourse, soared more than 20% on debut Wednesday as the appetite for Gulf listings heats up.

“Today we mark a significant milestone for our transformation,” Saudi Tadawul Group CEO Khalid Al Hussan told CNBC’s Dan Murphy on Wednesday.

Priced at 105 Riyals ($27.99) per share and oversubscribed by 121 times, the stock exchange operator opened at 115.4 riyals on Wednesday, 10% above the company’s listing price.

“Demand was significant for all types of investors — local, [regional] and international,” Al Hussan said, adding that public funds, Saudi corporates and sovereign accounts from the Gulf and globally, as well as retail investors, took part in the offer.

The share sale raised as much as $1 billion for the group’s only shareholder, the Public Investment Fund, which is tasked with investing to diversify the Saudi economy and advancing the kingdom’s Vision 2030 agenda.

“The listing is in line with one of PIF’s objectives to enable the financial sector by offering various investment options in the Saudi capital market,” said Yazeed Alhumied, deputy governor of the PIF.

The Tadawul Group IPO, at least five years in the making, is the second-biggest of the year after the $1.2 billion listing of utility company ACWA Power in October. The float of Saudi Telcom’s internet service unit in September also drew significant investor interest, underscoring hot demand for Saudi floats.

“The momentum of the transformation of the kingdom and the opportunities for Saudi corporates to grow and benefit from such transformation played a great comforting factor for investors to invest in these companies,” Al Hussan said.

Both the Dubai Financial Market and Abu Dhabi Exchange announced plans to shift trading days from Sunday to Thursday to Monday to Friday, in response to the UAE government’s decision to change its working week from next year. Saudi Arabia and the rest of the region currently follow a Sunday through Thursday trading schedule.

Al Hussan said the exchange operator was “keeping a very close eye” on the UAE’s decision to change its market trading days, but no decision had been made yet to follow the UAE’s lead.

“We won’t be reacting to a decision that was made by the UAE yesterday,” Al Hussan said.

“We continue to look at our trading hours,” he added. “From a capital market perspective, we haven’t seen concerns, as we speak, by international investors on the gap between trading days on the U.S. and Saudi Arabia.”

Economic competition between the UAE and Saudi Arabia has intensified through the coronavirus pandemic.

Regional commercial capital Dubai plans to take 10 state-backed companies public in the coming years, while Abu Dhabi has also seen a run of high profile IPOs this year, and possibly more in the pipeline, helping to send the bourse up almost 80% year-to-date.