HSBC - "1. No Tapering
G10: SELL USDJPY; SELL USDCHF. Safe havens such as the CHF and JPY would likely be favoured in this environment.
EM: Sell rallies in INR and IDR. EM FX may enjoy an announcement effect rally on this outcome. However, any rally would likely be short-lived as the Fed has only delayed the inevitable.
2. Just Tapering
G10: BUY GBPUSD, BUY NZDUSD. Continuation would likely be the market play on this largely consensus outcome. This points to modest USD selling against EUR and GBP which have already seen some strong gains. The JPY and CHF would likely be somewhat weaker, with USDJPY pushing back above 100. No obvious marked implications for "risk on" G10.
EM: Sell USDMXN. (...) We would remain cautious on the INR and IDR.
3. More Than Just Taper
If the Fed can successful drive US rate expectations lower from current levels, this would provide a potent boost to "risk on" and also foster a weaker USD. The biggest 'bang for your buck' in this scenario would be to buy those EM currencies which have suffered the most. (...)
G10: BUY AUDJPY & other JPY crosses. Safe havens would suffer on the upbeat mood of "rates lower for longer". AUD could outperform as the most liquid candidate for this revitalised mood, but NZD would track closely too.
EM: Sell USDMXN, Sell USDINR, Sell USDIDR, Sell USDZAR....etc (...) In the EM space at this time of the day, the MXN may be the "Go To" EM currency."