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The European Central Bank is assessing a key element of its stimulus plan that looks likely to gain in prominence next year.

The ECB is reviewing its corporate-bond buying program, according to euro-area officials familiar with the matter. The study by the Market Operations Committee is largely looking at the effectiveness of the strategy, which has spent 126 billion euros ($148 billion) so far, and how it influences the supply of credit to the euro-area economy.

At the same time, policy makers have discussed whether the benefits are skewed toward large firms and their shareholders, the officials said, asking not to be named as the is confidential. The ECB said in an emailed statement that it is “constantly monitoring the impact of its asset-purchase programs.”

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The evaluation comes as the ECB prepares to decide how to implement the slowdown in quantitative easing that will start in January. With the total program set to surpass 2.5 trillion euros by September, and some nations facing a shortage of the sovereign debt which makes up the bulk of purchases, the proportion allocated to corporate bonds could rise. President Mario Draghi said last month that buying of private-sector securities will remain “ sizable.”

The corporate-sector purchase program was a late addition to QE, starting in June 2016 as the central bank stepped up its drive to revive inflation. Buying of government and agency debt began in March 2015 and purchases of covered bonds and asset-backed securities began as smaller initiatives in 2014.

Debt Usage

The ECB currently buys 60 billion euros a month of debt, of which about 50 billion euros is from the public sector and 7 billion euros is corporate. Covered bonds and asset-backed securities make up the rest.

Monthly buying will drop to 30 billion euros in January, opening the prospect of allowing corporate purchases to make up a larger share. Draghi noted in an address to European lawmakers on Monday that this has happened before, when the ECB reduced its monthly bond-buying pace from 80 billion euros in April.

Some policy makers have questioned whether large companies, which have the greatest access to bond markets, are using cheap cash to finance share buybacks rather than boost investments, according to the officials.

Capital expenditure among European companies is expected to remain flat this year, then grow modestly in 2018 for the first expansion in five years, according to analysts at UBS Group AG.

Other policy makers see the program as providing indirect support to small and medium-sized enterprises that don’t tap the capital markets, the people said, echoing a point made by the ECB in its Economic Bulletin in June.

“Favorable bond-market conditions have resulted in positive spillover effects which have supported bank lending,” the central bank said then. “When large corporations increasingly finance themselves through bond issuances, rather than bank loans, this releases capacity in the balance sheets of banks for potential lending to SMEs.”

—With assistance from Sofia Horta e Costa.

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