The 10-year treasury yield briefly fell below 1.15%, trading at its lowest level since February, before settling at 1.17%, down 6.6 basis points from Friday.
The 30-year treasury yield also fell to 1.85, while the 2-year treasury not rate dropped to 0.18.
Kathy Jones, chief fixed income strategist at Charles Schwab, told CNBC a surge in COVID-19 cases amid the presence of the Delta variant could be a reason for the declines.
“I think the whole world expects yields to move up, and maybe that’s why they can’t,” said Jones.
The seven-day moving average of COVID-19 was above 63,000 on Monday, near its highest level since April, according to data from the Centers for Disease Control and Prevention.
To combat the rising cases, President Joe Biden on Thursday announced all federal government workers and contractors will be required to attest to their vaccination status and those who are unvaccinated will be subject to frequent testing and other restrictions.
On Monday officials announced transit workers in New York City and certain healthcare workers in neighboring New Jersey will be required to be vaccinated against COVID-19.
The S&P 500 has posted gains for six consecutive months after an increase of 2.3% in July, while the Dow Jones climbed 1.3% and the Nasdaq gained 1.2%.
Markets are also anticipating the July jobs report on Friday and quarterly earnings from Lyft, Amgen, Uber, CVS Health, General Motors and Roku throughout the week.