Several large buy-out contracts that were announced at the beginning of the year but were reported in the second quarter drove the second quarter's growth, said Eugene Noble, a research analyst at LIMRA, in a press release.

“We expected more activity in the pension risk transfer market as plan sponsors take advantage of the ability to make tax-deductible contributions at a higher rate before the new rates kick in as a result of the tax reform law,” added Noble.

In May, FedEx announced a $6 billion risk transfer deal, the largest single purchase since 2012, when General Motors transacted a $26 billion purchase and Verizon a $7.5 billion purchase.

FedEx's annuity purchase accounted for about 20 percent of its U.S. pension obligations, and transferred about 41,000 pensioners, or 15 percent of participants in U.S.-based pensions, from its books.

Analysts at Russell Investments said that reduction in headcount will lower FedEx's flat rate premiums to the Pension Benefit Guaranty Corp. by $3 million per year.

The FedEx deal was also notable because it was transacted with MetLife. Prior to the deal, the so-called “jumbo” risk transfer market had been dominated by Prudential, which had transacted the four largest single annuity purchases. The FedEx deal is the third largest transfer behind the GM and Verizon purchases.

Analysis from BlackRock shows that about 30 percent of pension sponsors with at least 1,000 participants had participated in some form of risk transfer activity between 2011 and 2016.

Most of the activity in 2014 and 2015 was accounted for by lump-sum payments to retirees after new mortality tables were incorporated into calculating future liabilities.

De-risking activity in 2017 was dominated by annuity buy-out purchases that targeted small portions of retirees that were set to become more expensive after PBGC premium increases took effect, according to BlackRock.

Nearly three-quarters of sponsors surveyed in BlackRock's 2018 Global Pension Survey said they are in the process of de-risking pension liabilities, with 40 percent indicating a desire to transfer risk.

Annuity buy-outs totaled $23 billion in 2017—a notable amount given the absence of jumbo buy-outs.

The $8.2 billion in sales in the second quarter is expected to be followed by an active third quarter, as sponsors have until September 15 to write off annuity purchases at the previous corporate tax rate.

While the trend of corporations' overall interest in de-risking pension obligations is indisputable, relatively few plans have been fully terminated. BlackRock's analysis of Form 5500 filings between 2011 and 2016 shows less than 6 percent of 3,000 plans with at least 1,000 participants were terminated in that period.