Photo courtesy of XL Fleet.

SPACs are under attack. The Wall Street Journal today rounded up the short-selling activity surrounding special purpose acquisition vehicles, the path to going public that's in vogue these days.

About 250 SPACs were launched in the U.S. last year and they've gotten hotter this year, drawing questions over the quality of the overall mix. Short sellers are also going after the companies that the SPACs ultimately take public. Here are some of the main points from the WSJ article:

• Data from S3 Partners shows bets against SPACs have risen in value to $2.7 billion from $724 million this year alone.
• Some 19% of the outstanding shares of Chamath Palihapitiya's Social Capital Hedosophia Holdings VCorp (IPOE) have been sold short, according to S&P Global Market Intelligence data. That makes it one of the more popular targets of short sellers who are betting against SPACs. Social Finance, Inc., better known as SoFi, announced in January that it planned to go public through a merger with Social Capital Hedosophia Holdings V.
• Another target is Churchill Capital Corp. IV (CCIV), which plans to take electric-vehicle startup Lucid Motors public. Short interest has more than doubled this month to about 5%.
• Short seller firm Muddy Waters threw down the gauntlet on XL Fleet Corp (XL), a maker of electric drive systems for commercial fleet vehicles. Muddy Waters described XL as "middle of the fairway SPAC garbage," and said the company had exaggerated its backlog of orders, and questioned the competitiveness of XL's technology. XL Fleet issued a rebuttal of the Muddy Waters report, calling it "grossly inaccurate." XL Fleet went public last year through a merger with Pivotal Investment Corporation II. "SPACs are an area of focus," Carson Block of Muddy Waters told WSJ.
• Another short seller firm, Hindenburg Research, last week went after electric truck maker Lordstown Motors Corporation (RIDE). "Lordstown is an EV SPAC with no revenue and no sellable product, which we believe has grossly misled investors on both its demand and production capabilities," Hindenburg tweeted when announcing a report against Lordstown. General Motors Company (GM) has a small stake in Lordstown, which went public via a SPAC deal with DiamondPeak Holdings Corp last year. Lordstown does not appear to have issued a statement in response yet.

This is the second time Hindenburg has targeted a SPAC-launched electric vehicle maker with ties to General Motors. Last September, Hindenburg called electric truck startup Nikola Corporation (NKLA) a fraud just days after GM and Nikola announced a major partnership that would have given GM an 11% stake in

Nikola. Nikola founder Trevor Milton stepped down as chairman later that month. GM and Nikola re-entered an agreement later in November, with the GM equity stake removed.