HSBC research note on the impact of negative rates, saying the effect on economies is complex and the result therefore for FX is unclear.

Negative interest rates contribute to a breakdown in the relationship between rates and FX

  • don't have a notably direct negative impact on FX
  • may even mean that FX markets start to pay even less attention to rates, rather than worrying about them more

More:

  • currencies weaken iwhen traders anticpate negative rates. but the impact lessens soon after they take effect
  • little evidence of negative policy rates causing deposit outflows
  • negative rates are not new
  • market is focused on relative interest rate differentials