Is the big bond boom over?

Bill Gross says so:

The 10-year U.S. Treasury yield climbed to the highest level in more than nine months, leading Bill Gross at Janus Henderson Group to declare a bond bear market just ahead of a deluge of sovereign debt sales.

The benchmark U.S. yield rose as much as six basis points to 2.54 percent, a level last seen in March, and the Treasury curve steepened the most in three weeks, as a looming glut of bond supply from the U.S., the U.K., Japan and Germany coincided with a surprise cut in purchases of long-dated Japanese government bonds by the Bank of Japan.