Global banking giant Citibank (Citi) has partnered with SIX Digital Trading Platform (SDX), the digital assets arm of Switzerland's leading securities exchange, to tokenize untraded shares, aiming to simplify the $750 billion market, which still relies on PDF files and paper documents. Citibank will act as custodian and issuing agent to provide a tokenised version of late-stage, unlisted company stakes on SDX's regulated blockchain platform, the Central Securities Depository (CSD).