* Avg GRM falls to $4.32/bbl from $9.98/bbl last yr
* Shares rise as much as 6.7 pct after results (Adds details, background)
Aug 3 (Reuters) - Indian Oil Corp Ltd said on Thursday net profit fell 45 percent in its fiscal first quarter of 2017, beating analysts' estimates, as higher inventory losses and lower refining margins weighed on profitability.
Net profit was 45.49 billion rupees ($714.83 million) in the quarter ended on June 30, compared with 82.69 billion rupees a year earlier, the country's top refiner said. (http://bit.ly/2v21dfw)
Analysts on average had expected a net profit of 30.63 billion rupees for the first quarter, Thomson Reuters data showed.
The company's quarterly average gross refining margins, or profit earned on each barrel of crude processed, eased to $4.32 per barrel, compared with $9.98 per barrel in the same period last year.
Global oil prices kept fluctuating during the quarter but overall international benchmark Brent crude futures declined 9.3 percent.
IOC shares were up about 5 percent as of 0900 GMT while the broader Nifty 50 index was 0.48 percent lower. ($1 = 63.6375 Indian rupees) (Reporting by Aby Jose Koilparambil in Bengaluru; Editing by Christian Schmollinger)