Do antivirus companies share signatures among themselves?

Question

Malware

I am writing a program in Delphi. 2007. Kaspersky swears at a certain line in the code. After changing this line in the code, the antivirus stops cursing. I decided to send the exe file of the program, which is not detected by Kaspersky, to the laboratory with the mark - suspicious software.
So what do you think? New signatures from Kaspersky have arrived. And exe that was not detected by the virus. Suddenly became a virus. As I understand it, they take the md5 hash of the file in Kaspersky and stupidly hammer it into signatures?
Changed again the code in the program. Kaspersky again does not find viruses. A question. Does Casper send his "brave signatures" to other antivirus companies? This exe file is not detected in other antiviruses.

Answer 1

Signatures are not shared. There are false positives. And life is pain and everything is decay.

Answer 2

Signatures are not shared. Share copies. The process of obtaining signatures from instances is the know-how of every antivirus company.
The other day there was a scandal that LK allegedly shared something under the guise of malware that broke the work of competitors.

Answer 3

In fact, a virus database is the biggest secret of any antivirus manufacturer - why give it to competitors for free?

Answer 4

And what does your program do that should be detected by antivirus?
After all, anti-virus companies do not add all the files that the user sent them to the databases.
Signatures are not specific pieces of code, but certain semantics. So one signature can detect several viruses written in different languages.

Answer 5

they exchange exactly files that they consider malicious (with some delay)
another example is services for checking files on-line with several antiviruses, from which files get to interested companies