Does it matter if the stock you buy comes in the form of a token on a blockchain? We could soon find out as the Securities and Exchange Commission is reportedly moving forward on a plan to let companies offer stock trading “on chain.” The plan would be a boon to firms like Coinbase and Robinhood, which are raring to expand their crypto offerings, but could also pose a risk to investors, according to major financial companies like Citadel Securities, which are demanding the agency slow-roll the plan.