A good start to US corporate earnings season and a deal in Greece was lifting sentiment on Tuesday morning, with the FTSE 100 expected to open with strong gains early on. City sources predict London's benchmark index will open up 40 points from yesterday's close of 6,450. Wall Street stocks finished broadly higher on Monday night as investors geared up to the start of second-quarter earnings season after the opening bell. Aluminium producer Alcoa didn't disappoint, reporting adjusted earnings per share of seven cents, ahead of the six cents forecast, though consensus forecasts had been trimmed in the lead-up to the results given recent falls in metal prices. The firm posted revenue of $5.85bn for the second quarter, slightly lower than $5.96bn the year before but in line with estimates.Meanwhile, it was announced last night that finance ministers in the Eurozone have granted Greece its first instalment of its next tranche of aid, worth €2.5bn, if it meets prior conditions. Greece will also get a further €500m in October.Stocks to watchMarks & Spencer's struggling general merchandise division showed some improvement in the first quarter, the retailer revealed in a trading update on Tuesday. General merchandise, which includes clothing, achieved a 0.5% rise in sales after the group unveiled a new strategy to turn to the business around.Quality solutions group Intertek has acquired Melbourn Scientific, a specialist pharmaceutical products testing business, for an unspecified amount.Soft drinks firm Britvic today confirmed that the Competition Commission has formally approved its possible merger with AG Barr. "The CC's final decision is that the possible merger is not expected to result in a substantial lessening of competition," Britvic said in a company statement.