When there is a stock split (forward or reverse), the options are adjusted to reflect the terms of the split. In this case, the new option root symbol for adjusted options is USO1.
Below is the OCC memo that explains the adjusted option. I can't provide the link because since I am registered with the OCC, my name is in the web address link. If you want to see the post at the OCC's web site, google "OCC USO option split".
DATE: APRIL 22, 2020
SUBJECT: UNITED STATES OIL FUND, LP – REVERSE SPLIT
OPTION SYMBOL: USO
NEW SYMBOL: USO1
United States Oil Fund, LP (USO) has announced a 1-for-8 reverse stock
split. As a result of the reverse stock split, each USO Common Share
will be converted into the right to receive 0.125 (New) United States
Oil Fund, LP Common Shares. The reverse stock split will become
effective before the market open on April 29, 2020. Cash will be paid
in lieu of fractional USO shares.
Effective Date: April 29, 2020
Option Symbol: USO changes to USO1
Contract Multiplier: 1
Strike Divisor: 1
New Multiplier: 100 (e.g., for premium or strike dollar extensions
1.00 will equal $100)
1) 12 (New) United States Oil Fund, LP (USO) Common Shares
2) Cash in lieu of 0.5 fractional USO Shares
CUSIP: USO (New): 91232N207
Until the cash in lieu amount is determined, the underlying price for
USO1 will be determined as follows: USO1 = 0.125 (USO)
The USO component of the USO1 deliverable will settle through National
Securities Clearing Corporation (NSCC). OCC will delay settlement of
the cash portion of the USO1 deliverable until the cash in lieu of
fractional USO Shares is determined. Upon determination of the cash in
lieu amount, OCC will require Put exercisers and Call assignees to
deliver the appropriate cash amount.