Early indications suggest that Wall Street stocks may open on a cautious note on Friday, capping off a volatile week. The Labor Department’s non-farm payrolls report for May due ahead of the open is key to how the markets fare in the last trading session of the week. Economists widely expect another month of solid job gains and the unemployment rate to remain largely unchanged. Bond yields have pulled back and oil is weaker ahead of the OPEC meeting due later in the day. Meanwhile, the mood in the markets across the Atlantic is markedly weak, as Greek worries continue to strangulate risk appetite.