This morning, Spark's share price was down 8 cents (1.84 per cent) to $4.27 soon after the market opened.
When asked about the issue, Ardern said she was aware of the problems and had read some of the discussions around what happened.
She said she still has confidence in the telco – "based on the fact they have contingency plans in place".
Spark made the game freely available on TVNZ's Duke channel when the problems were discovered.
When pressed further on the matter, Ardern said the issues were a matter for Spark.
Ardern's take on the streaming saga was a lot more diplomatic than her deputy, Winston Peters – who is Acting Prime Minister while she is overseas this week.
He said the streaming of the game was an "abject disaster".
And he vowed the Government will get to the bottom of the issue.
"I can assure you we will find out as fast as possible as to what on earth is not going on," he told Newstalk ZB's Weekend Collective yesterday.
Peters – who was forced to watch much of the game on his phone as the stream on his TV was interrupted – said Spark should have been better prepared for the event.
"They [Spark] were told to get ready and we hoped that they would be ready and they promised us that they would be and they're not.
"It's not satisfactory."
Ardern was at the game on Saturday in Japan, watching it live.
Asked if she enjoyed the match, Ardern said she found it "very tense".
The All Blacks won 23 – 13 in the World Cup opener.