Additionally, despite the cancellations, the government still had 17 successful ruble bond auctions this year and its relatively low external debt burden of around $3 billion in repayments this year can easily be funded from its $480 billion of foreign exchange reserves, Shearing said.
The real concern is with Russia's companies and banks, which face around $83 billion in external debt repayments by the end of the year, he noted.
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"Unlike the government, most firms do not have large external assets to fall back on," he said, but he noted the government may step in to assist any systemically important companies.
Over the past week, Russia's corporate bonds within the Emerging Market Corporate Index have seen their yields rise around 79 basis points, according to data from Barclays. Bond yields move inversely to prices.
Still, not everyone is equally bearish over the impact of sanctions on Russian corporate finances.
"In general, companies have a strong financial position and good liquidity. The country and the large corporations should be able to deal with the situation, even if further sanctions are imposed (assuming oil and gas still flows to the Western world and China absorbs other commodities from Russia)," Emiliano Surballe, a fixed income analyst at Julius Baer, said. But the bank is advising sticking to relatively short duration of up to four years in the strongest corporates.
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Barclays also isn't advising joining an exit from Russian sovereigns, keeping a neutral call in its emerging market credit portfolio and a recommendation to buy Russia's 2030 bonds. While the geopolitical concerns in Russia are a "clear negative" for the country's credit markets, Barclays expects most investors to stay neutral.
"Investors seem caught between the risk of any potential legal ramifications of further sanctions and cheap valuations (the latter notwithstanding the adverse long-term economic implications of the sanctions for the Russian economy)," it said.
—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1