Two major firms are warning that the low number of deals year-to-date heighten concern for the markets during the seasonally weak six months spanning May through October.

“An increasing number of charts in our work depict levels that are only prior to a bear market,” according Savita Subramanian and her team at Bank of America Merrill Lynch.

Even if the Fed stays on hold, other markets are tightening, according to Subramanian. Among other things, equity IPOs year-to-date are near an all-time low.

Subramanian points out that there have been only 12 IPOs year-to-date, the lowest since 2009. IPO proceeds to date are the lowest since 2003.

Tobias Levkovich and his team at Citigroup also highlighted the slowdown in merger & acquisition activity as worrisome.

"M&A activity often has preceded equity market trends and the number of deals has fallen off meaningfully,” he wrote. “Higher financing costs, especially in the junk bond world, have put a damper on transactions not to mention government intervention on inversions and antitrust aspects. While financial conditions have improved over the last three months, tracking takeovers may become more important to the stock market."

Subramanian added that the deals slowdown has coincided with an increase in corporate buybacks, which tend to “top-tick” the market. “The proportion of companies buying back shares is near all-time highs, at the same levels as the ‘07 peak,” she wrote.

While both Subramanian and Levkovich pointed to heightened uncertainty — led by the U.S. presidential election, negative corporate profits, Brexit uncertainty in Europe, and oil moves — both temper their negativity.

“Bull markets typically end with euphoria and aggressive positioning in stocks. Our Sell Side Indicator suggests sentiment is at bearish extremes, which is bullish for stocks,” Subramanian wrote. Levkovich added that the Panic/Europhia Model is back in panic territory, which implies a 97% chance of higher equity markets in a year.