The　large-scale　promotion　online　brings　great　challenges　to　e-tailers,　such　as　the　uncertain　demand　caused　by　strategic　customer　behaviors　and　the　unreliable　supply　from　suppliers.　In　this　article,　a　portfolio　procurement　strategy　(PPS)　that　incorporates　a　long-term　contract　and　a　spot　market　is　proposed.　From　the　perspective　of　a　risk-averse　e-tailer,　we　identify　conditions　under　which　the　e-tailer　should　procure,　via　the　unreliable　supply　contract　only,　the　spot　market　only,　or　both.　The　impacts　of　risk　aversion　and　strategic　customers　on　the　optimal　procurement　strategy　are　also　investigated.　The　results　show　that,　when　procurement　price　via　contract　lies　between　two　thresholds,　the　e-tailer　chooses　PPS,　and　otherwise　chooses　supply　contract　or　spot　market　only.　The　PPS　is　more　likely　to　be　used　if　the　e-tailer　is　more　risk-averse,　the　supply　is　more　unreliable,　or　there　are　more　strategic　customers.