Why is Tata motors sales down but stock up ?

Why is Tata Motors sales down but stock up? 

According to recent headlines in news, Tata Motors domestic sales are down nearly 10%. Everyone expected that the share price would go down, but instead, it has gone up today - 02 Jan 2020. Why?

On the first day of the year 2020, it was the trending headline in most of the news channels- Tata motors sales down. It was expected that the stock would go down on the next day that is on 02 Jan 2020. But the stock market gives surprises. While almost all auto stocks went down on Thursday, Tata Motors went up by almost 5%, a massive single-day jump. The following chart demonstrates the same.
Tata motors stock goes up
Day chart shows the movement of Tata motors stock in past 3 months
It is evident from the chart that there was a massive jump in the Tata motors stock price today despite the news of its sales going down. 
Well, in the same news, it was also mentioned at the end that the company has been planning to shift from BS IV to BS VI. And that its stocks of BS IV will likely finish and the company will soon start rolling its BSVI vehicles. 
Further if you note the trend since Sept 2019, the sales have started to improve. In Sept 2019, sales were down 48 % compared to same month last year, In November it was down 25% compared to November 2018 and in Dec 2019, it was down only 10% compared to Dec 2018. 
So you can see from the trend, the downtrend in the sales of vehicles has started to improve and it seems that in next 2-3 months, the growth will again pickup and we will see the sales going up. 
Hence in the expectation of a better future, the stock has already started going up. 
We can see here that although the news looks negative on the face of it, looking at the long term broader perspective, it becomes a positive news. So we need to understand the news in the right perspective before reacting on every small news that comes your way. 

Hope you understand the market well and invest wisely. 

Happy investing.