Why have IOCL and BPCL not gained despite robust GRMs?

It looks like in the recent GRM rally, the gains have gone to smaller players like Chennai Petro and MRPL. Why is it that IOCL and BPCL did not gain to that extent? Here is why BPCL and IOCL have not gained in trading. They have refining and marketing as their core business. Now comes the problem. The GRM boosts refining profits but the retailing profits are negatively impacted by the prices of petrol and diesel not rising in tandem with crude oil. That is where the pure refiners score but the integrated OMCs lost out.

The bigger question is whether this kind of a trend is really sustainable? That may be difficult since the record GRMs were a result of shortfalls in refining capacity caused by the Russia-Ukraine war. If things sober down, it may be back to more normalized levels of GRMs. That could worsen the situation for the likes of IOCL and BPCL since GRMs will come down but marketing margins will still be under pressure. That is what the OMCs or the downstream oil companies have to be very cautious about.