multimapping reads Kallisto

[Caroline Juery]

Hi everybody, 

I am using kallisto to counts reads on a reference transcriptome. I try to search how kallisto manage the multimapping of reads and I could see two type of answers on forums and webpages : 

1) discard the multimapped reads

2) add fractions of counts to several transcripts / genes

What is the truth ? 

Thank you all for your help