Mahboob - I noticed that Monday Jan 20 shows no activity for both US & Canada, Tuesday Jan 21 shows all High Valuation stocks as newly at High valuation, etc for both USA & Canada.  Monday Jan 20 was a holiday in US. It was not however a holiday in Canada

Would there be a way of detecting easily a day when markets for a particular country were closed, and so then comparing against last day when markets were actually open? 

Something like a spotcheck of just the Top20/8 stocks - if no change in prices at all for the group, then market must have been closed....
 