Unexpected cut output

I am getting an unexpected output from cut. I would expect no output since there is no third field based on the specified delimiter. The first two lines intentionally use commas as delimiters, and the third uses both commas and semicolons. I know how cut generally works, but I was trying to show that this shouldn't produce output in this example but it is. input file: students.txt

Fred,Jones,sophomore
Mary,Adams,freshman
Sam,Fredrick;senior

cut command:

cut -f3 -d ';' students.txt

unexpected output:

Fred,Jones,sophomore
Mary,Adams,freshman