LONDON (Reuters) -Chevron Corp said on Monday it would buy smaller rival Hess Corp in a $53 billion all-stock deal, taking its rivalry with Exxon Mobil to the next level by boosting its presence in U.S. shale and oil-rich Guyana.

Following are reactions from analysts and investors:

ROYAL BANK OF CANADA

Given that Exxon Mobil had effectively taken itself out of the running for large-scale M&A following the recent Pioneer deal, we would have thought Chevron could bide its time, and hence we are a little surprised at the timing of this deal.

It does address the concerns with Chevron's portfolio - namely over concentration in the Permian and lack of depth in growth elsewhere, however it comes at a price given the relative multiples between the two companies.

In the end, Chevron walks away with a stronger, more diversified portfolio, which should bode well for shareholders over the long term, but in the near term, the news could weigh on the shares.

MKP ADVISORS

Hess has been touted as a potential target for the super-majors for some time; it had been mainly the stance of John Hess as a non-seller that was perceived as the reason why this has not happened before. Entering his 70th year, it seems he has got to the point where he sees a transition of Hess to a new ownership structure is appropriate.

Perhaps, we once again get some pushback about the concept of large scale U.S. super-majors pivoting back to fossil fuel exposure rather than building out renewables etc, but this is more a topic for Chevron’s shareholders and management rather than a threat to this deal.

PETER MCNALLY, THIRD BRIDGE

The recent flurry of acquisition activity from Chevron and Exxon Mobil reminds Third Bridge experts of the building of the "super majors" that began 25 years ago, an era that transformed the oil industry into the massive companies that we see today.

Back then, the super majors were consolidating to drive costs lower. Today, the companies being acquired today like Hess and Pioneer Natural Resources have more concentrated asset bases and expertise built in developing specific resources.

VIKTOR KATONA, KPLER

Hess has minimal presence in the Permian basin yet is one of the leading producers in the Bakken basin in North Dakota, so Chevron is expanding its outreach rather than zooming in on one specific play.

The transaction might also create a peculiar coexistence of the United States' two leading oil majors in Guyana... Suddenly Chevron becomes a big player in Guyana just as the country is ramping up production towards the 1 million bpd (barrels per day) threshold.