The calls to EntityValue that feed FinancialData would look like this,

EntityValue[{
  Entity["Financial", "NASDAQ:QCOM"],
  Entity["Financial", "NASDAQ:LIN"],
  Entity["Financial", "NYSE:TMO"]},
 {EntityProperty["Financial", "Name"],
  EntityProperty["Financial", "MarketCap"]}]

Still coming up Missing. The direct call into a single Entity does work.

Entity["Financial", "NASDAQ:LIN"]["MarketCap"]

This example creates a series of direct calls.

AssociationMap[
 #@EntityProperty["Financial", "MarketCap"] &,
 {
  Entity["Financial", "NASDAQ:QCOM"],
  Entity["Financial", "NASDAQ:LIN"],
  Entity["Financial", "NYSE:TMO"]
  }]