Markets have a busy day ahead on Wednesday with a batch FTSE 100 companies out with interim results and a slate of economic data.Tullow Oil and British American Tobacco will take centre stage on the company front with their latest earnings reports. The first of the two is releasing its half-year results and according to Investec on Monday the company has its work cut out with exploration on the back foot and divestment and portfolio management catalysts pegged for later in the second half. The broker reiterated a 'sell' rating for the stock, saying exploration is not meeting expectations and further funding needs to be considered for pending deals and developments. British American Tobacco announced on Monday that it will enter the electronic cigarette market. It has become the first tobacco company to launch the product in the UK, raising fears that it could eventually boost its profits with public money should the NHS begin prescribing the electronic cigarettes as a smoking-cessation tool.The company is likely to address the development further in its interim statement.Turning to macro-economic news, the US will hog the spotlight as the Federal Reserve announces its interest rate decision at the end of its two-day policy meeting. Markets will keep close watch to see whether the central bank will reveal when it will begin its planned tapering of its $85bn a month bond buying programme. The Fed has kept its rate near zero since 2008 and has said it plans to leave it unchanged so long as unemployment remains above 6.5% and inflation outlook below 2.5%. Unemployment is currently at 7.6% and the inflation rate is at 1.0%.Also on Wednesday, the country's gross domestic product (GDP) figures and MBA Mortgage Applications report will be unveiled. The economy grew at a 1.0% annualised rate from April to June, after expanding at a 1.8% pace in the previous quarter, according to the median forecast of economists surveyed by Bloomberg.Wednesday July 31stINTERIMS4Imprint Group, Aer Lingus Group, British American Tobacco, Centrica, Devro, Dignity, Essentra, First Quantum Minerals Ltd., Genel Energy, HydroDec Group, Millennium & Copthorne Hotels, Rightmove, St James's Place, Tarsus Group, Taylor Wimpey, Tullow OilINTERIM DIVIDEND PAYMENT DATEChrysalis VCT, Schroder UK Mid Cap FundINTERIM EX-DIVIDEND DATEAndor Technology, B.P. Marsh & Partners, Brunner Inv Trust, Fenner, Impellam Group, Japan Residential Investment Co Ltd., Microgen, Nichols, Porvair, Throgmorton TrustQUARTERLY PAYMENT DATEJP Morgan Chase & Co, Middlefield Canadian Income PCC, Schroder Income Growth FundQUARTERLY EX-DIVIDEND DATECity of London Inv TrustINTERNATIONAL ECONOMIC ANNOUNCEMENTSChicago PMI (US) (13:45)Crude Oil Inventories (US) (15:30)FOMC Interest Rate (US) (17:15)GDP (Advance) (US) (13:30)International Reserves (EU) (11:00)MBA Mortgage Applications (US) (12:00)Unemployment Rate (GER) (08:55)Q2First Quantum Minerals Ltd., Smurfit Kappa GroupFINALSAngleANNUAL REPORTAtkins (WS), Greene KingIMSSBrewin Dolphin Holdings, Greencore GroupSPECIAL EX-DIVIDEND PAYMENT DATEAberforth Geared Income Trust, Archipelago ResourcesAGMSBetter Capital Pcc Ltd (2009), CML Microsystems, Creon Resources, Cropper (James), Environmental Recycling Tech., Hansa Trust, Hyder Consulting, Mytrah Energy Ltd, Parallel Media Group, Ram Active MediaTRADING ANNOUNCEMENTSTaylor WimpeyUK ECONOMIC ANNOUNCEMENTSBalance of Payments (09:30)BRC Shop Price Index (00:01)Current Account (09:30)FINAL DIVIDEND PAYMENT DATEAcal, Crawshaw Group, Edinburgh Inv Trust, Panther Securities, Record, Rensburg AIM VCT, Zhejiang Expressway Co 'H' SharesFINAL EX-DIVIDEND DATEAberdeen New Dawn Inv Trust, Creston, Energy Technique, Hasgrove, Investec, JPMorgan Euro Small Co. Trust, Latham (James), SSERD