Sigma EF530 DG ST and Wireless ETTL

Could somebody tell me if the Sigma EF530 DG ST will work as a slave for either the Canon 550eX, or alongside it fired by the ST-E2. I've got the Canon gear I mentioned, but I think I need another remote flash and I'm wondering if the Sigma will operate with the Canon gear.

Thanks in advance.

no
sigma st does not have a slave sensor

The EF530 DG ST doesn't, the EF530 DG SUPER will work both as a wireless E-TTL slave and as a "dumb" optical slave.

Thanks,
Your replies clear that up for me. Time to shop for something else.