In[]:=
data=TimeSeries[FinancialData["SBUX","Close",{{2013,1,1},{2013,12,1},"Week"},Method->"WDF"],TemporalRegularityTrue]
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TimeSeries
Time: 04 Jan 2013 to 29 Nov 2013
Data points: 48

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DateListPlot[data,FrameLabelAutomatic,Filling->Axis]
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In[]:=
eproc=EstimatedProcess[data,ARIMAProcess[2,1,1],ProcessEstimator->"MaximumConditionalLikelihood"]
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ARIMAProcess[0.119791,{0.718876,-0.155833},1,{-0.845138},0.448337]
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forecast=TimeSeriesForecast[eproc,data,{26}];
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DateListPlot[{data,forecast},Filling->Axis]
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