Today the 3-year Treasury note was auctioned for 4.2% annual yield. That's not a bad rate of return for a risk-free investment (assuming held to maturity). At least it's not completely laughable -- I mean, it wasn't that long ago that short-term bonds paid 1% or less. If rates continue to rise, at what point to investors seriously begin to shed stocks and buy Treasuries? 5%? 6%? 8%? never?