NEW YORK (TheStreet) -- Stocks slipped slightly from session highs achieved shortly after the Federal Reserve confirmed it would be "patient" in determining when to raise rates and that a rate hike earlier than the next couple of months was unlikely.

"The committee considers it unlikely to begin the normalization process for at least the next couple of meetings," said Fed Chair Janet Yellen in a conference. "This assessment, of course, is completely data dependent."

The Fed kept its previous phrase "considerable time" in the statement but only in saying that its new phrasing is "consistent" with previous language. "This new language does not represent a change in our policy intentions and is fully consistent with our previous guidance," she said, noting the change in language was to better reflect an improving economy and tightening labor market.

Stocks extended gains after rallying on positive sentiment heading into the Fed announcement. The S&P 500 added 1.3%, the Dow Jones Industrial Average climbed 216 points, and the Nasdaq gained 1.4%.

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The statement comes at a time of increased volatility in the marketplace against a backdrop of plunging oil prices, softer domestic housing data, weaker economic figures coming out of China, and the Russian economy in freefall.

Crude prices recovered from deep losses suffered earlier after Russian officials said 2015 output would be similar to this year's at 10.6 million barrels a day. West Texas Intermediate was up 3.6% to $57.94, though remaining at nearly half of the mid-summer peak.

"It's not the bottom. We're going to have these bounces. There's short covering in the futures market," said Jeff Sica, CIO of Circle Squared Alternative Investments, in a call. "We're going to see a continuation of the selling based primarily on the fact that there's significantly less demand than anyone anticipated... It's way too soon to call bottom on oil prices." 

Crude oil inventories fell 0.8 million barrels last week, according to a release Wednesday from the Energy Information Administration. Economists had expected a drop of 2.4 million after an increase of 1.5 million barrels a week earlier.

Large-cap oil stocks including Exxon Mobil (XOM) - Get Report , Chevron (CVX) - Get Report and Royal Dutch Shell (RDS.A) rallied. The Energy Select SectorSPDR ETF (XLE) - Get Report spiked 3.7%, though it remains more than 12% lower for the year.

The Russian ruble steadied after two days of steep declines as Russian authorities initiated the sale of their foreign exchange reserves. Earlier in the week, Russia's central bank enacted an emergency interest rate hike of 650 basis points to 17% after the currency suffered its worst intraday drop in 16 years.

In an address Wednesday, President Obama said the U.S. will restore diplomatic relations with Cuba and open an embassy in Havana for the first time in half a century. Earlier, American contractor Alan Gross was released from Cuban prison after being held captive for five years.

Herzfeld Caribbean Basin Fund (CUBA) - Get Report , which invests in companies in countries within the Caribbean Basin including Cuba, rocketed around 34% higher at volume more than 700 times its daily average.

"Recently, President Obama stated that Gross' release is necessary for him to begin implementing a series of actions to help the process of reconciliation. I believe this is an important first step toward this process," Chairman Thomas Herzfeld said in an email. "We have made every effort to position the Herzfeld Caribbean Basin Fund to benefit from resumed trade with Cuba."

American Apparel (APP) surged more than 15% after the company terminated controversial former CEO Dov Charney's employment, six months after he was ousted as head of the company. Paula Schneider has been named as his replacement.

Volcano (VOLC)  exploded 55% after Phillips (PHG) - Get Report announced it was acquiring the medical equipment developer for $18 a share, a 57% premium to Tuesday's close.

Tesla (TSLA) - Get Report was bucking earlier losses after Morgan Stanley reduced its price target to $290 and cut the company's estimated unit deliveries through to 2020. Shares were 3.8% higher.

FedEx (FDX) - Get Report shares were down more than 4% after missing second-quarter earnings and revenue expectations. The company reiterated its previous full-year forecast and said it expects a "modest" boost from lower fuel prices. Competitor UPS (UPS) - Get Report moved lower in sympathy.

Cliff Natural Resources (CLF) - Get Report tumbled nearly 9% as Credit Suisse slashed its price target to $1 from $10, noting current consensus estimates are "nearly double" where they should be.

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--Written by Keris Alison Lahiff in New York.