IMHO, as the article discusses a forming bubble in Treasuries and as VFTSX holds few Treasuries (I believe less than 10% of the fund), the article doesn't apply directly to VFTSX holdings. From the article, you could surmise this to be a good time to buy VFTSX as Treasuries have rallied to "bubble" characteristics at the expense of pretty much the entire rest of the bond market (including short term corporates, mortgages, cmbs, abs, and other VFTSX type holdings).