Stocks moved slightly higher Tuesday as nerves peaked over how the Federal Reserve and the Bank of Japan will vote in their separate two-day meetings.

The S&P 500 was up 0.25%, the Dow Jones Industrial Average added 0.25%, and the Nasdaq rose 0.3%.

Speculation over the Fed's likelihood of moving on interest rates sooner rather than later has caused waves on Wall Street in recent weeks. A rush of weak data, including snapshots of retail, industrial and inflation numbers for August, have pushed out the chances of a hike to later this year, though Fed members continue to spout more hawkish rhetoric.

The chances of a rate hike in September sit at 15%, according to CME Group fed funds futures. Most analysts are betting on a rate hike in December, which has a 48% likelihood.

The FOMC is set to meet for two days beginning Tuesday, culminating in an announcement, forecasts and press conference from Fed Chair Janet Yellen on Wednesday afternoon.

"A more assertive Fed will emerge at this week's FOMC meeting," said Peter Cardillo, chief market economist at First Standard Financial. "While we don't believe the policy makers will raise rates at the upcoming meeting, we foresee a more hawkish group emerging to prepare the markets for a rate increase in December."

The Bank of Japan was also on watch as members meet for a two-day discussion on monetary policy. Unlike the Fed, market analysts are mixed on whether the central bank will make a move, including increasing stimulus, this month.

Housing construction fell below estimates in August as recovery in the housing sector came in fits and starts. Housing starts fell 5.8% from July, coming in at a seasonally adjusted annual pace of 1.14 million, according to the Commerce Department. Analysts expected an annual pace of 1.18 million. Permits came in flat at 1.14 million.

Crude oil prices fluctuated on Tuesday as earlier hopes began to fade that a production freeze agreement between Organization of Petroleum-Exporting Countries could come to pass. Worries over international supply have dragged on prices since oil began its descent more than a year ago.

West Texas Intermediate crude oil closed 0.3% higher at $43.44 a barrel.

Tobira Therapeautics (TBRA) soared 710% after Allergan (AGN - Get Report) agreed to purchase the biopharma company in a deal worth $1.7 billion. Allergan agreed to pay $28.35 a share upfront, in addition to payment for certain milestones. The deal is expected to close by the end of the year.

Allergan is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells AGN? Learn more now.

Lennar (LEN - Get Report) reported a positive quarter on the back of overall strength in the U.S. housing market. Quarterly profit rose to $1.01 a share over the quarter, up from 96 cents a share a year earlier. Analysts had expected profit of 89 cents a share. Revenue climbed 13.7% to $2.83 billion.

SeaWorld (SEAS - Get Report) slid 4% after suspending its dividend in order to buy back stock. The theme park operator will pay its final dividend to shareholders on Oct. 7. SeaWorld has struggled in recent years over its controversial captivity of orcas and has since agreed to phase out the practice.

Chesapeake Energy (CHK - Get Report) fell 2% after activist investor Carl Icahn cut his stake in the company to 4.55% as of Monday. Icahn had previously held a 9.4% stake as of August 4. 

Ascena Retail Group (ASNA - Get Report) tumbled 30% after issuing a far weaker outlook than anticipated. The owner of the Ann Taylor brand anticipates full-year earnings of 60 cents to 65 cents a share, below estimates of 83 cents a share. Sales are expected to come in no higher than $7 billion, roughly $200 million below forecasts.

Pier 1 Imports (PIR - Get Report) climbed 1% after Alden Global Capital disclosed a 9.5% stake in the homewares retailer. The firm said it believes Pier 1 is at a "critical juncture." Alden is speaking with management to secure representation on the board.

Wells Fargo (WFC - Get Report) rose 1.4% as CEO John Stumpf apologized to the Senate Banking Committee for the bank opening unauthorized accounts to drum up sales numbers. Stumpf also said the company will extend its internal review back as far as 2009. U.S. regulators charged the company $185 million last week over illegal sales practices. The bank now plans to eliminate sales targets beginning next year.

Wells Fargo is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells WFC? Learn more now.

HD Supply (HDS - Get Report) was downgraded to sector perform from outperform at RBC Capital. The firm said the company will likely take several quarters to fix the supply chain and restore investor confidence.