NO This is a bad idea which could get you in trouble.
The way to handle it is to go back and say something along the lines of sending an email to your current manager, copying in anyone appropriate asking for approval to share the document.
Update from comments:
I want to make it clear that there should be no doubt in your mind that sending the document is a bad idea.
Ensure your boss knows that you know that and that you never would without express permission.
You can even mention you are concerned it is a phishing attempt.
If you want to keep yourself out of it, you can just forward the email onto your boss.
It may be completely innocent and all above board, or it may be dodgy but you'll want written permission by someone with the authority to give it.
Treat all company documents as company property (because they are)
this isn't really your decision to make.
If your ex-manager chases in the mean time you can just say: "I'm just waiting on approval for your request".
If he kicks off, you know something fishy is going on.
workplace.stackexchange.com/users/105591/Bee
No, you should not share your company documents with people who are not working for your company and/or don't have written permission to access them.
workplace.stackexchange.com/users/66740/Tymoteusz Paul
so my ex manager who left our company recently called me up a couple of days back to share a document.
Are you someone who makes decisions for your company on what documents to share with outsiders?
If not, then this is a red flag.
However, im confused whether or not I should share it as he could have easily copied it and taken it while he was working here or in his notice period
but he is asking me to do it now.
Most contracts have clauses saying that if you leave the company you're not allowed to take company documents with you.
If he'd copied the document during his notice period, he would have been liable.
This is somewhat a confidential doc you can say as its related to sales.
Sales documents aren't just "somewhat" confidential; most companies consider them key competitive/strategic information.
He said his new company where he is working is different and does not have any similarity to us however he wants this document just for reference.
Doesn't matter.
He's not with the company, he doesn't have any right to company confidential data.
Even if you don't know about any bad thing he might do with them.
They're confidential, that's all the reason you need to deny him.
I find it a bit fishy
and im worried if this might affect our business or Im I just overreacting?
He's asking you to do something now, that if he had done himself back then, could have gotten him sued.
Right now, it could get you fired and/or sued.
Yeah, it's fishy.
As an aside: what constitutes confidential data?
As a rule of thumb, any data not available to the general public.
Sales prices for consumers: not confidential.
Sales prices for business customers who are getting a special discount or have some kind of cheap grandfathered contract: confidential.
The real prices at which you purchase stock (perhaps with a discount because you're a big buyer): confidential.
Which products are going on sale next month: confidential.
Which products are on sale right now: not confidential.
Current sales figures: confidential.
Sales figures published in a press release: not confidential.
You should consider whether you should warn your current manager that your former manager is snooping around and asking for this document.
If he gets hold of it, perhaps from someone else careless, suspicion might fall on you (since you have access and knew him).
workplace.stackexchange.com/users/111679/ObscureOwl
This person is trying to steal confidential information by spear phishing .
Report this behaviour to your superior immediately.
The fact that he does not have access to this document is intentional.
If your company wanted ex-employees to be able to access documents, it could easily set this up.
workplace.stackexchange.com/users/79283/knallfrosch
Your ex-manager doesn’t work at the company anymore and has no rights whatsoever to these documents.
Tell him as politely as you like that you are not going to send these documents to him.
If he tries to reason with you tell him as politely as you like that you are not going to send these documents.
Also inform your manager and HR about the request, in case he approaches others.
Do NOT tell that you thought about sending these documents for even a second; sending them would quite likely get you fired on the spot.
workplace.stackexchange.com/users/16101/gnasher729
My ex manager who left our company recently called me up a couple of days back, and asked me to share a document. This is somewhat a confidential doc, as it relates to sales.  He could have easily copied it himself before he quit, but he is asking me to do it now. He says he wants this document just for reference.   I find it a bit fishy, and I'm worried if this might affect our business. Am I just overreacting?
Should I share a somewhat confidential document with my now ex manager? (They had access before leaving the company.)
workplace.stackexchange.com
<ethics><manager><workplace-rhythm>
workplace.stackexchange.com/questions/149891
workplace.stackexchange.com/users/112833/Trinket
You should not share company documents with someone who doesn't have permission to access them. It could get you in trouble. You should definitely not share any confidential documents with ex-employees, regardless of who they are.
You should definitely not share any confidential documents with ex-employees, regardless of who they are.