this._exposureService.listAllExposures
  .subscribe(
    res => {
      this.allExposureData = res;
    }
  )
;

res: [
{
    companyId: 1,
    reportDates: [
        {
            reportDate: 12/31/2017,
            currencies: [
                {
                    currency: 'USD'
                }, ...
            ]
        }, ...
    ]
}, ...