Xi Jinping’s corruption crackdown on China’s growing financial sector is accelerating. It now reached the upper levels at some of China’s premier institutions and creating further concerns for investors that have to fight more and more headwinds for the world’s second largest economy.

At least 16 officials have been probed or penalized in April. That comes on top of dozens of financial officials that have been ensnared since October.

The latest move has made investing in China more difficult as Xi’s crackdown on a broad range of private industries, including real estate and big technology companies, continue. Resurging COVID-19 cases also further suppress the economy, putting the government’s 5.5% growth target at risk.

Authorities on Friday announced a probe of high ranked executives from banks, government controlled financial institutions and China’s market regulator.

China’s top disciplinary body criticized more than two dozen financial regulators and state banks in February, saying they had common problems including prominent corruption around key positions and areas. Regulators including the People’s Bank of China as well as the financial institutions named had pledged to rectify the problems.

Xi has continued to press ahead with his signature anti-corruption drive after almost a decade in power, most recently focusing on law enforcement. The campaign has over the years brought down more than 1.5 million government officials.