GENEVA — Ten years after an international treaty banned cluster munitions, several financial institutions are slashing investment in companies that produce the weapon, according to a European organization that campaigns for a global ban.

The Netherlands-based group PAX said in a report released on Monday that financial institutions it monitors had cut investment in companies that produce cluster munitions from $31 billion in 2017 to $8.7 billion in 2018 — a 72 percent decrease.

Michel Uiterwaal, a co-author of the report, called the downturn a “testament to the growing global awareness that support for this weapon is unacceptable.” But he also said that many companies not covered by the report were continuing to produce and invest in cluster munitions.

“The global problem is much worse than we describe,” Mr. Uiterwaal said, “because there are more producers and there’s more money involved.”