The Galaxy S10e lost an average of 50.2% across all storage options in 30 days, the S10+ lost 47% and the S10 lost 42.7% in value, says BankMyCell.
This makes the phone "one of the fastest depreciating handsets since 2017," the report said.
Video: Which Galaxy S10 phone should you buy?
"On a depreciation percentage basis, the Galaxy S10 range lost more in the first month [than] the iPhone XS/XR range has in 9 months," BankMyCell said.
Hardest hit was the S10e 128GB model, which fell from $750 new to just $350 in trade-in value after 30 days. The Galaxy S10+ 1TB phone went from being worth $1,600 to only $750 at trade in.
The report predicts the S10 will lose 65% of its value by March 2020.
Samsung didn't immediately respond to a request for comment.