The answer provided by rhermans at StackExchange was perfect!
Module[
{
names = {"GS", "MS", "BAC"},
dates = {{2000, 1, 1}, {2000, 1, 20}},
filename = "spreadsheet.xls",
data
},
data = Map[
Transpose[
Prepend[FinancialData[#,
dates], {# <> " date", # <> " value"}]] &, names];
File@Export[filename, Transpose[Flatten[data, 1]]]
]
