Can propensity score matching be applied to a single year to get a constant control sample?

[Ray Du]

I am trying to get a matched sample for a group of firms experiencing some one-time event (e.g., IPO). I would like to find a matched firm for each IPO firm using PSM, and then conduct a DiD analysis. I am conducting the PSM before the event for each treated firm. Once I find a control firm, I keep the treat-control samples constant, and study DiD. Is this correct? I am asking this because in most empirical literature, researchers have conducted PSM on a panel (e.g., firm-years), instead of a cross-section of firms. Thank you!

[Jared Greathouse]

Do you observe firms multiple times before and after the intervention? Do you have more than 10 periods of pre-intervention outcome data for all units?

[Ray Du]

Do you observe firms multiple times before and after the intervention? Do you have more than 10 periods of pre-intervention outcome data for all units?

Yes I observe firms multiple times for each firm, and for treated firms pre and post intervention. For control firms, there is no intervention to start with, so I am not sure what you mean. Thanks.

[Jared Greathouse]

Why not use synthetic controls