But the kingdom has pared back important but painful domestic economic reforms and been distracted by its blockade of Qatar and long-running war in Yemen. Now the abrupt internal purge — ousting economic technocrats, a billionaire prince and other members of the royal family — has left experts wondering whether it is truly aimed at corruption or at Mohammed's political rivals.
"The kingdom is at a crossroads," Bruce Riedel, director of the intelligence project at the Brookings Institution and author of the forthcoming book "Kings and Presidents," said in an email. "Its economy has flatlined with low oil prices; the war in Yemen is a quagmire; the blockade of Qatar is a failure; Iranian influence is rampant in Lebanon, Syria and Iraq; and the succession is a question mark. It is the most volatile period in Saudi history in over a half-century."
One key test will be the planned initial public offering of a roughly 5 percent slice of Saudi Aramco. The crown prince has promoted the offering as a way of showing that the kingdom could be transparent and that it had to diversify its economy.
The crown prince, who met President Trump in the Oval Office in March, has been selling his Vision 2030 plan to leverage the kingdom's global oil power into broader economic development at home. During Trump's visit there in May, Saudi leaders and the American president highlighted deals to promote manufacturing in the kingdom., not just purchases of equipment. Most of those deals were still being negotiated and the final amount will probably be a fraction of the totals announced.
Jared Kushner, the president's adviser and son-in-law, made an unannounced visit to Riyadh last week.
"Trump is tying his regional policy to an increasingly unstable leadership," Riedel warned.
Since Trump's visit, the Saudi government has continued to search for investors. Just recently, there was a major investment conference in Riyadh. Last month, Mohammed announced plans to build a new city in the country's northwest financed by $500 billion in investments.
Yet as part of the weekend shake-up, Adel Fakeih, the minister of economy and planning and a member of Saudi Arabia's oversight council, was dismissed.
Gregory Gause, head of the international affairs department at the Bush School of Government and Public Service at Texas A&M University, said in an email that the wave of arrests goes to the heart of the investment issue and called the timing "puzzling."
"If this means a new definition of 'corruption' in the Kingdom, I think that it will take awhile for both the domestic private sector and foreign investors to figure out what is going on," he said. "In the meantime, I think they are going to be cautious about investment. And investment and private sector growth are what Vision 2030 are all about."
Investors will be looking carefully at plans for the Aramco IPO. So far it hasn't been clear whether the IPO would be launched in London or New York.
On Saturday, President Trump tweeted: "Would very much appreciate Saudi Arabia doing their IPO of Aramco with the New York Stock Exchange. Important to the United States!"
But recently many Saudi experts, who believe Saudi Aramco's books hide large payments to the royal family, doubt that the king and crown prince will be able to make the offering transparent enough for international investors. Now, the shake-up will give investors further pause. Some analysts believe a private placement with Chinese or Russian companies is a possibility.
"I think [the shake-up] does to Aramco what it does to the whole notion of foreign investment in the economy — raises red flags," Gause said. "But one of those red flags on Aramco might be China's!"
For now, the public offering is on track. "President Trump's tweet suggests the IPO may not be dead as reported," Robert McNally, president of the Rapidan Energy Group consulting firm, said in an email.
Some even think that the wave of arrests is a sign that the IPO and tough economic reforms could continue, even if that means disclosures about wrongdoing at Saudi Aramco.
King Salman bin Abdul Aziz on Saturday named Mohammed head of a corruption "supreme committee" in addition to a council that oversees Saudi Aramco, which in the past had been governed largely by technocrats. Salman said the move was because of "what we have noticed of exploitation by some of the weak souls who have put their own interests above the public interest, to, illicitly, accrue money."
Ibrahim al-Assaf, a former finance minister and current director of Saudi Aramco, was among at least 17 princes, current and former government ministers and business executives taken into custody, according to a Bloomberg News report quoting the al-Eqtisadiah newspaper. Assaf was arrested on charges of corruption linked to an urban expansion project in the city of Mecca, Bloomberg News said, citing the Akhbaar 24 local news website.
"In my view the arrests signify that the Crown Prince has decided to really use the corruption button to discipline the royal family," Jean-François Seznec, a specialist in Middle East business and finance, said in an email. Seznec, who has taught at Georgetown University's business and foreign service schools, said: "The King is the one who knows where all the skeletons are buried in the Royal Family. By striking hard against princes known to be corrupt, and large business people known to have been close to the corrupt, he is putting the family on notice that they will have to go along with the notion of transparency in business and control of society."
He said that the crown prince "knows that only if he can place the family under the law, and not above as it was in the past, can he ask the whole country to change their attitudes relative to taxes [and] subsidies."
But Riedel said the anti-corruption drive will be discredited if it looks like a tool for punishing Mohammed's political opponents.
Investors are also looking for other signs of domestic reforms.
The International Monetary Fund said in July that the kingdom would run a deficit of about 9.3 percent of gross domestic product this year. Unemployment was running around 12.3 percent. It said that non-oil growth was projected to pick up to 1.7 percent but that relatively weak oil prices would keep overall GDP growth "close to zero."
The Saudi government had also vowed to cut generous subsidies for energy, food, social services and clerics. But fearful of domestic opposition, the subsidy cuts were shelved.
"So far the Saudis have reversed course on lowering public sector salaries and reducing subsidies, which were very unpopular, and instead emphasized social changes in entertainment and women's driving that don't change the Kingdom's over-dependence on oil income," Riedel said. "That is why they are heading into recession."
The importance of the desert kingdom will be on display at the Organization of the Petroleum Exporting Countries meeting on Tuesday. The Saudis, the world's biggest exporter, will dominate the session, showing just how important its 10 million barrels a day of crude oil are to the global economy — even with the surge in U.S. oil output in recent years.
Saudi Arabia is curtailing production enough to slowly drain world oil inventories and nudge prices higher. That stance has started paying off as global oil prices recently crept over $60 a barrel. Oil experts expect little to no change now.
Oil prices were relatively steady on Monday. The international bench mark Brent crude was $62.55 a barrel, up 48 cents, at 10:25 a.m. The price of the bench mark West Texas Intermediate was $55.92 a barrel, up 28 cents.
"Saudi Arabia may no longer be the oil market's swing producer but still has large influence in energy markets, regional affairs and international finance," said McNally, who served on President George W. Bush's National Security Council.