Here are five things you must know for Thursday, Sept. 21:

1. -- Gold prices slumped to a three-week low Thursday, Sept. 21, as investors moved cash into higher-yielding assets following a hawkish market reaction to the Federal Reserve's signals on future interest rate hikes. 

Gold prices fell 1.45% to $1,297.30 an ounce, the first dip below $1,300 since late August. The SPDR Gold Trust EFT (GLD) - Get Report , which has gained 12.8% so far this year, declined 0.5% in premarket trading to $122.97.

The U.S. dollar index, which measures the greenback's strength against a basket of six global currencies, was trading down 0.03% to 92.42. It has risen more than 1% over the past two weeks in anticipation of the Fed's meeting on Wednesday, Sept. 20.

U.S. stock futures pointed to a weaker start for Wall Street on Thursday after the Fed left interest rates unchanged, as expected, and also said it would begin unwinding its massive balance sheet, beginning with a reduction of up to $10 billion a month. However, plans call for that amount to increase by $10 billion a quarter and reach $50 billion a month by this time next year. The Fed holds $4.5 trillion in Treasury securities and mortgage-backed assets on its balance sheet. 

One surprise was that Fed officials sounded far more hawkish on the future path of rate hikes. Investors had predicted that the Fed would slow the pace of rate hikes as the U.S. economy faces consistently soft inflation, coupled with wage growth that's stuck in neutral. But 12 of the 16 FOMC members said in Wednesday's communique they anticipate a third rate hike this year, while 11 of the 16 anticipate three hikes next year.

Following the Fed's announcement, the Dow Jones Industrial Average and the S&P 500 climbed 0.19% and 0.06%, respectively, to close at new records. The Nasdaq fell 0.08%. 

The economic calendar in the U.S. on Thursday includes weekly Jobless Claims at 8:30 a.m. ET, and the Philadelphia Fed Business Outlook Survey for September at 8:30 a.m.

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2. -- Alphabet Inc.'s (GOOGL) - Get Report  reached a deal valued at more than $1 billion to buy part of the smartphone division of Taiwan's HTC Corp.

Google will pay HTC $1.1 billion and receive a non-exclusive license for HTC intellectual property, while certain HTC employees, "many of whom are already working with Google to develop Pixel smartphones -- will join Google," the companies said in a joint news release. 

The agreement highlights plans by Google to push further into the handset market. HTC has been a long-time contract manufacturer for Google, most recently helping it launch its Pixel smartphone, which debuted last year.

The deal was expected, and HTC's stock was halted Thursday before the announcement.

The companies said the transaction, subject to regulatory approvals, is expected to close by early 2018.

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3. -- The Securities and Exchange Commission revealed late Wednesday that hackers breached the market regulator's system used to store and record the filings of public companies, and that some people might have profited by illegally trading on that information. 

Jay Clayton, the chairman of the SEC, issued a statement detailing the hack, which the agency said was first detected last year. But it wasn't until August that the SEC learned about the possibility of hackers trading on the information. 

"Our investigation of this matter is ongoing, however, and we are coordinating with appropriate authorities," Clayton said in the statement. 

The statement added: "In August 2017, the commission learned that an incident previously detected in 2016 may have provided the basis for illicit gain through trading. Specifically, a software vulnerability in the test filing component of our EDGAR system, which was patched promptly after discovery, was exploited and resulted in access to nonpublic information." 

"We believe the intrusion did not result in unauthorized access to personally identifiable information, jeopardize the operations of the commission, or result in systemic risk," Clayton stated.

4. -- Tesla Inc. (TSLA) - Get Report  is getting closer to developing its own chip for handling autonomous driving tasks in its cars, CNBC reported.

The electric carmaker has received back samples of the first implementation of its processor and is now running tests on it, a source familiar with the matter told CNBC.

Tesla has been working to decrease its reliance on other companies, CNBC noted, but Tesla won't completely be going it alone in chip development and will build on top of intellectual property from Advanced Micro Devices Inc. AMD.

Tesla shares were flat in premarket trading on Thursday.

AMD shares declined 1% in premarket trading after gaining nearly 5% on Wednesday.

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5. -- Western Digital Corp. (WDC) - Get Report  said it would pursue legal action to bar Toshiba Corp.'s (TOSBF) plan to transfer its interests in three NAND flash-memory joint ventures it operates with Western SanDisk subsidiaries to a consortium led by Korea-based SK Hynix Inc. and Bain Capital LP.

Western Digital said Wednesday  that several of its SanDisk subsidiaries have filed an additional request for arbitration with the ICC International Court of Arbitration related to three NAND flash-memory joint ventures operated with Toshiba.

Jim Cramer Reveals Why He Sold Western Digital For His Charitable Trust

Western Digital bitterly criticized Toshiba's signing of a transfer agreement with the Bain group, which was announced Wednesday, in a deal valued at $18 billion.

This story has been updated from 6 a.m. ET.

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