U.S. companies are buying back record amounts of stock this year, but their shares aren’t getting the boost they bargained for. Today’s investing advice will explain the drawbacks in this strategy.

S&P 500 companies are on track to repurchase as much as $800 billion in stock this year, exceeding even 2007’s figures. The biggest names here include Oracle (ORCL), Bank America (BAC) and JPMorgan (JPM).

But of the more than 350 companies in the S&P 500 that bought back shares so far this year, nearly 60 percent are trailing the index’s 3.2% boost. We haven’t seen this many companies fall short of benchmark performance since 2008, according to a Wall Street Journal analysis of buyback and performance data from Factset.

It’s well-known that stock buybacks have been among the primary contributors for the solid stock performance in the US in 2018, largely thanks to Trump’s tax reform which allowed companies to use repatriated cash to repurchase stock. However, the following chart from Bank of America published last week shows just how pervasive the buyback wave had been so far in 2018. As it shows, the bank’s clients deployed record amounts of cash to repurchase their own stock.

One week later, BofA’s Client Flow monitor provides an update, finding that ahead of the earnings season blackout, buybacks by corporate clients have slowed down modestly to a six-month – in line with seasonal patterns – but YTD still remain +101% YoY and continue to suggest a record year for buybacks.

But while corporate buybacks may be fading into earnings, the total buyback activity throughout the first half of 2018 reveals a surprising picture. As shown in the most recent “Chart of the week” from BofA, which lays out first half sector flows, corporate clients’ buybacks were the largest buyers within Financials ($10.6bn), Tech ($10.5bn), Health Care ($6.5bn), Consumer Discretionary, and Industrials.

And the historic spending spree on share buybacks has some analysts worried. Companies seem to be buying their shares at excessive valuations during the peak of the economic cycle, and at a time when the market rally is nine years old. Others warn the billions of dollars spent to buy back shares could have gone toward capital improvements like new factories or technology that could lead to stronger long-term growth.

“There has been less of a reward for companies engaging in new buybacks over the last 18 months,” said Kate Moore, chief equity strategist and a managing director at asset-management firm BlackRock Inc. “It’s fair for investors to ask whether companies are buying at the right point.”

The S&P 500 Buyback index, which tracks the share performance of the 100 biggest stock repurchasers, has gained just 1.3% this year, well underperforming the S&P 500.

This proves what many have suspected. Without buybacks, there would be little buying pressure on stocks. This is a problem, because with just days left until buyback blackout period, the buyer of last resort for US stocks is about to go on a month-long vacation, just as the trade war between the US and China begins.

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