The Straits Times Index (SGX: ^STI) has slipped below the 4,300 mark, after spending most of September above this level.When volatility strikes, an income investor can look to defensive stocks that have stable earnings and dividends.Here are three defensive Singapore blue-chips you can consider, namely Singapore Exchange or SGX, Singapore Technologies Engineering or STE, and Singapore Telecommunications or Singtel.Singapore Exchange (SGX: S68) SGX is Singapore’s sole stock exchange operator. The group enjoy ...