Tobias Levkovich, chief US equity strategist at Citigroup, reminds investors to prepare for increased volatility. The Fed's downsizing, possible tax rate increases, margin pressure, and continued inflation may become “pressure the bond market will have to respond to.”

“We're a little more careful,” he said in an interview with Bloomberg TV, adding that at a time when valuations are high, these four potential problems “may pour down on each other around September.”

Lori Calvasina of Crown Capital Market, Tobias Levkovich, Citi's chief US equity strategist, and Erin Browne, Pimco's multi-asset strategy portfolio manager, discuss the Federal Reserve's asset purchase plan.

Levkovich's target point for the S&P 500 index at the end of the year is 4,000 points, showing his pessimism about current market conditions. His target is more than 10% below the all-time high set by the S&P 500 last Friday.

He believes that the $550 billion infrastructure bill awaiting approval by the House of Representatives will not give much boost to the economy because “pure infrastructure is less than 25%.” “This isn't the big plan that everyone wants.”

Some investors are concerned that the turmoil in Afghanistan may damage market sentiment, but Levkovich believes this will not pose much of a threat to the market.

“Geopolitical events often complicate things, and even when you know there are risks, it's usually hard to predict,” he said.