what could topple Bulls' Wall of Worries'

--Stocks can still flourish through investors are nervous. It is climbing a wall of worry - rising to record heights despite deep worries that anyone of serveral risks could send it tumbling. --what could topple Bulls market a.skittishness over high risk securities and subprime market blow up subprime is a small corner of the total credit market. leveraged loans will be a potential concern. It might clog the PE deals pipeline. b.inflatilon - no brainer for me c.weak dollar - double edge sword d.liquidity - it is another concern given the fact that some investors are pulling money out of their hedge funds and PE funds. The situation might be building due to the concerns of blow up of two BSC hedge funds.