According to the NY Fed System Open market Account Holdings page, the Federal Reserve has purchased approximately $650 billion in Treasury securities thus far in Q2 (starting April 1 2020). These consist of Treasury notes, bonds and T-bills. The holdings rose from approximately $3.1 trillion to about $3.75 trillion. The Fed has purchased these securities in the open market with newly created USDs in what is essentially an asset swap with the banking system - USD reserves for bonds. Meanwhile, the US Treasury, according to the Treasury Direct website, has issued about $1.6 trillion