U.S. stocks mixed in a tame conclusion to a wild week of volatility

The Dow fell slightly on Friday, while the NASDAQ and S&P 500 posted modest gains

Investing.com -- U.S. stocks ended one of the most volatile weeks in recent memory with a relatively tame close on Friday, as comments from an influential Federal Reserve governor on the likelihood of a September interest rate hike pushed stocks slightly lower.

Speaking exclusively with CNBC, Fed vice chairman Stanley Fischer indicated that recent U.S. economic data had been impressive providing a compelling argument for short-term rates to head in a higher direction. Without explicitly stating that the U.S. central bank will raise its benchmark Federal Funds Rate next month, Fischer said the Fed could not wait for the case to be "overwhelming" before hiking rates above its current level of zero to 0.25%. Fischer also indicated that temporary headwinds that have caused recent volatility in global markets could recede quickly.

The Dow Jones Industrial Average fell mildly on Friday, while the NASDAQ Composite and S&P 500 Composite index posted slight gains to cap a roller coaster week of volatility among the major U.S. indices. U.S. stocks suffered their worst one-day decline in four years on Monday, before rallying in the middle of the week to complete their strongest two-day gain since the end of the Financial Crisis on Thursday. The Dow closed the week at 16,643.01 after losing 11.76 or 0.07% on the session, while the NASDAQ added 15.62 or 0.32% to close at 4,828.33.

The S&P 500, meanwhile, gained 1.21 or 0.06% to 4,828.33, as five of 10 sectors closed in the green. Stocks in the Energy and Basic Materials industries led, while stocks in the Healthcare, Financials and Utilities sectors lagged.

The top performer on the Dow was Chevron Corporation (NYSE:CVX), which gained 2.55 or 5.64% to 80.19, as crude oil futures extended a massive rally from Thursday's session when it surged by more than 10%. Over the past two days, U.S. crude futures have soared by more than 15% to above $45 a barrel. The worst performer was Pfizer Inc (NYSE:PFE), which fell 0.73 or 2.19% to 32.53.

The biggest gainer on the NASDAQ was Southern California-based videogame maker Activision Blizzard Inc (NASDAQ:ATVI), which rose 1.58 or 5.64% to 29.51 after making its debut on the S&P 500. The worst performer was Autodesk Inc (NASDAQ:ADSK), which fell 2.56 or 5.12% to 47.44, following its acquisition of Cloud-based software developer SeeControl.

On the S&P 500, the top performer was Alcoa Inc (NYSE:AA), which gained 0.50 or 5.64% to close at 9.36. Alcoa extended gains from one session earlier after a Federal judge strongly considered throwing out a 2013 lawsuit against the aluminum giant on Thursday related to the closure of a North Carolina hydroelectric dam several years earlier. The case revolves around whether Alcoa owns the clear title to the riverbed, where it built four dams – all of which could net the company billions of dollars if it decides to sell them in the near future. The worst performer was Gamestop a, which lost 3.97 or 8.59% to 42.23.

On the New York Stock Exchange, advancing issues outnumbered declining ones by a 2,034 to 1,108 margin.