The answer to your question will be a SAS format for both usage scenarios. The difference is that PROC PRINT will need a FORMAT statement:
format invest comma10.2;
While the PUT statement just needs to be told what format to use:
PUT invest= comma10.2;
If you used a format statement inside your DATA step program, then WORK.NEWDATA would have the format permanently associated with the INVEST variable. For example, in the program below, the WEIGHT variable in WORK.NEW has the format COMMA10.6 associated with it. So, that format is used by PROC PRINT.
format weight comma10.6;