The Heavenly Abacus

An investment bank risk controller transmigrates into the body of a demon cult leader, and immediately finds himself besieged at his gates by the righteous alliance. He knows no martial arts and can't be bothered with fighting and killing—he does only one thing: opens the account books and restructures the bad debt. In his past life he did risk hedging; in this life he runs a demon cult. With seventeen sects of the righteous alliance camped before the city, Gu Changgeng glances down at the Tianji Pavilion's balance sheet: ample cash, crushing external debt, and a demoralized inner circle. He resolves the siege with three proposals: itching powder to spark infighting within the alliance, preferred shares to bind the elders' loyalty, and debt restructuring to pacify his largest creditor—then turns around and starts shorting the entire northwestern martial world's weapons market. — Description from novelcodex.org