Saudi Arabia is ramping up efforts to lure high frequency trading firms — a campaign that’s already brought in major players from Citadel Securities to Hudson River Trading — as it looks to bolster activity on the Middle East’s largest stock market.

Saudi Arabia’s Crown Prince Mohammed Bin Salman told President Donald Trump he’s willing to expand investments and trade with the US in the coming four years by $600 billion, according to the kingdom’s state-run news agency SPA.

BlackRock Inc. is set to host a gathering of top corporate executives and government officials in Riyadh, marking the US firm’s first event on this scale in the Saudi capital and bolstering the kingdom’s efforts to lure foreign investment.

An escalating dispute over an OPEC+ decision to cut oil production risks causing lasting damage to political relations between the US and Saudi Arabia. Wall Street seems unfazed.