The merger of the two rival chains was blocked by Britain's Competition and Markets Authority in April, and Sainsbury's Chief Financial Officer Kevin O'Byrne told CNBC Wednesday that the group was "disappointed" with the outcome.
"The conclusion from the CMA that a combined Sainsbury's and Asda would increase prices, reduce service, extend queues etc. in one of the most competitive grocery markets in the world, and customers wouldn't go down the road to Tesco, Aldi, Lidl, Morrisons, Co-op, etc., is not a market we recognize," he said.
Sainsbury's fourth quarter to March 9 like-for-like sales fell 0.9%, having fallen 1.1% over the Christmas period. They declined by 0.2% over the full 2018-19 year.
However, underlying pre-tax profit for the year did exceeded expectations to rise by 7.8% to £635 million ($829 million), aided by synergies from the Argos general merchandise business it purchased in 2016. Shares rose by around 6% in early deals Wednesday.
The grocer also said it would increase and accelerate investment in its core business to improve over 400 supermarkets this year. It made a new commitment to reduce net debt by at least £600 million over the next three years.
O'Byrne also denied reports that the position of Sainsbury's CEO Mike Coupe was under pressure following the blocking of the merger.
"This was a deal that was unanimously agreed by the board," he said.
"We did a lot of research, we took a lot of advice on that as did Walmart. While this was never a dead cert, it was a high probability that this deal could be done. The management team are just getting on with running the business in what is a challenging market."
O'Byrne told CNBC that the group was "making lots of progress in areas where customers are moving their shopping habits," including its online and convenience areas of the business.
Responding to talks of a distribution agreement between Britain's fourth-largest supermarket chain, Morrisons, and Amazon Prime, O'Byrne said Sainsbury's could list its products with Amazon Prime "tomorrow" if it so wished.
"We have a very strong online business ourselves, so we don't think that's necessary," he added.
—Reuters contributed to this article.