Not generally, because few would define a market in terms of a single day since it's not very useful. Usually a period of one year is assumed but can commonly be a quarter or a month.

But technically, if you defined it that way, sure it had the biggest market share for that day.

That seems unlikely :-) But sure, for that day. Nobody measures market share for a day though, as it's not a useful metric.

what I find abyssmal is this story getting on the front page on HN and venturebeat, when it is already few weeks old.