I read a sentence "CFIUS has stymied several deals in the past year" in New York times. But I was taught that the present perfect should not be use if there is a word indicated the past time, and "in the past year" is not the past time?
The time expression "in the last year" continues up to and includes the present time, so there is no inconsistency between this time expression and the present perfect.
It would have been wrong to say "has styied... last year", but you can say "has stymied ... this year"
The author could also have used the past tense, because the time expression "in the last year also includes past time.