Invast Australia's latest Hot Note put a sell call on the shares, predicting Santos would soon fall to the mid-$3 range.
"“When the dust settles from the current oil price sell off, there will only be a few names in business. We're fairly confidant Woodside is one of those names, but not sure how much damage Santos will endure," the note said.
Invast said the oil price didn't appear to be bottoming out in the near future. It said Santos was one of the most vulnerable large caps in the sector.
"For that reason, we think momentum will continue to the downside - even if we see what some perceive to be ridiculously low levels," Invast said.
"The market is worried about energy and there is a lot of overhang stock now which can be easily placed into the market for a quick profit. We expect that scenario to play out."
A major brokerage firm has put a sell call on Santos shares, with further losses expected.