Stocks in London are set for a lower start on Thursday morning with City sources predicting the FTSE 100 will open 10 points lower than Wednesday's close of 7,007.26.Concerns about Greece continue to rumble on in the background following comments from the German finance minister that he could not rule out a Greek default.Meanwhile, ratings agency Moody's has warned Athens that without an agreement over a cash-for-reforms deal with creditors, the government will have to impose capital controls on its banks to stem an outflow of funds.According to reports, Greek prime minister Alexis Tsipras is expected to present a debt-restructuring proposal at a two-day summit of EU leaders which starts on Thursday in Riga.As for the economic data schedule, manufacturing figures from across the globe will be in focus as Markit presents its May 'flash' purchasing managers' indices (PMIs) for the Eurozone and US.Meanwhile, the HSBC China manufacturing PMI released overnight rose from 48.9 to 49.1 this month, showing that the rate of decline - measured by any figure below 50 - had slowed, though it still missed the consensus forecast of 49.3.A number of blue-chip stocks are set to go ex-dividend on Thursday, which will provide a further drag on the FTSE 100. Heavyweight constituents Bunzl, Carnival, HSBC, Intertek and Taylor Wimpey will go ex-div and collectively take 6.41 points off of the index.Stocks to watchRoyal Mail delivered a mixed bag of full-year results with numbers bang in-line with expectations but a somewhat cautious statement on the highly competitive market. At the reported level, showing only continuing operations, revenues were just about flat at £9.3bn, with pre-tax profit slumping by more than two thirds, as expected, to £400m and earnings dwindling to 32.5p from 127.5p a year ago, versus forecasts of 32.8p.Technology outfit Smiths Group has reiterated guidance for full-year growth in spite of a weakening of underlying results over the first three quarters. The company said its outlook for the year was unchanged from that given in March when it said it expected to "deliver improved underlying performance in the second half". However, underlying revenues and headline operating profit "fell slightly" on the previous year in the nine months to 2 May.Food wholesaler Booker announced on Thursday that it has signed a sale and purchase agreement to acquire the entire issued share capital of Musgrave Retail Partner, which comprises the Londis and Budgens businesses for £40m.