bang went sixpence

I am a german student, stuying english at a university.
I came across this saying and have been surfing the web and researching in numerous idiom collections, but i am unable to find out its meaning:
I'll give you the whole sentence:

James McLaren invested 50 grand in venture and bang went sixpence.

I am to find out whether, formally this one sentence could be a very short Short Story and thus i have to find out what the latter part means.

thanks in advance

[Marylin]

There is an idom bang goes something.
Bang goes something means - something has turned for the worse, something's gone.

ex.
If I don't get my knee looked at and fixed right away, bang goes my swimming for this summer! (= I can kiss my swimming good bye, there goes my swimming!).

James McLaren invested 50 grand in venture and bang went sixpence.

I am not sure if it's just a play on words based on that particular idiom.
"Bang" in slang also means luck/situation/ fortune
sixpense probably stands for something worthless.

paraphrasing this I get the same thing:
his luck/fortune turned sour (worthless) by investing all that money.