No it's not. Languages most commonly used in finance are: C/C++, Python, Java, Scala, Julia, Matlab, R, and KDB.

Where? Aside from the few OCaml fans, I’ve only ever seen bog-standard Java/C++/Python

I don't know about finance, but I think it's used heavily in aviation.

It's used heavily at Intel, in hardware verification.

Virtually all EDA (electronic design automation) tools include a Tcl shell that echoes back any GUI action as a Tcl command. This makes it very easy to write Tcl scripts that perform repetitive actions (e.g., load HDL source, compile design, simulate, check value of signal).

Aplusdev.org used the tk part. While APL is used heavily in many financial institutions I am not sure how widely A+ is used.

A+ was invented by Arthur Whitney for JP Morgan (iirc). I'm sure they have some things in house still using it, but that it's mostly been deprecated by Whitney's Kdb+ environment which is sold by Kx Systems. It is the APL like "K" language bundled with a database generally run on SSD. I believe it is quite pricey.

According to the aplusdev.org site it's Morgan Stanley. I have zero knowledge of what the current status is inside that or any other company.

Ah, similar name. Thanks for pointing out my mistake.