I am Japanese But SB can stands Standerd Bond (fiinacial words)
"K "many time I heard. Letter "K" Stand Kilo = Thousand I some time speak with native Engish speaker3K or 4K as mean of Thousand . Many Understanding Numbers usually we write as 1,000 like this therefore Letter" K" (KILO) can easy to understand amount.
I usually see Hk$ or others that is make diffinition bitween US$ and other$. This my opion.