Hot Topics in Tech: SEC says cyber security biggest risk to financial system. Fed should better safeguard economic data, internal watchdog says. A new trading floor in 2016? The options market turns to old tactic. CME upgrade soothes critics who viewed prior system as unfair. Nasdaq to unleash the machines on insider traders through Smarts investment. Why the SEC should just say "no" to IEX. Can a $24 Billion hedge fund blow the whistle? Citadel thinks so.

Blockchain Roundup: Inside the secret meeting where Wall Street tested digital cash. DTCC holds a blockchain conference. Microsoft Azure partners with R3 blockchain consortium. Red Hat announced the Open Shift Blockchain Initiative. CME Group bites on bitcoin, will now publish daily price.

The Inbox: Listener questions and comments

• Question from Jane Neal: Does Trade Alert or Whats Trading off data on futures?
• Question from George Constopolis: Why is most stock and options settlement still T+3? Can we not get that down to a more reasonable time frame with the current technology?