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Here are five things you must know for Tuesday, June 6:

1. -- U.S. stock futures declined and shares in Europe fell amid a weak U.S. dollar, rising political tensions in the Gulf region and electoral risks in the United Kingdom.

The U.S. dollar index, a measure of the currency's strength against six of its global peers, fell 0.5% to  96.75 as investors continued to react to softer data from the world's biggest economy and positioned themselves ahead of potential testimony Thursday from former FBI director James Comey.

Oil prices edged lower in the U.S. early Tuesday, down 0.2% to $47.39 a barrel, as a diplomatic row between Qatar and its Gulf neighbors intensified.

The economic calendar in the U.S. on Tuesday includes the Job Openings and Labor Turnover Survey for April at 10 a.m. EDT.

2. -- Earnings are expected Tuesday from Lands' End (LE) - Get Report , Fred's , Analogic (ALOG) , Ambarella (AMBA) - Get Report , Conn's (CONN) - Get Report , Dave &Buster's (PLAY) - Get Report , G-III Apparel (GIII) - Get Report , HD Supply Holdings (HDS) - Get Report and Michaels (MIK) - Get Report

Apple and Alphabet are holdings in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells AAPL or GOOGL? Learn more now.

3. -- Apple (AAPL) - Get Report shares were rising slightly in premarket trading on Tuesday, a day after the tech giant unveiled its new HomePod assistant and an analyst said the company's drive into services revenue could weaken its ability to raise iPhone prices over the longer term.

Apple unveiled its newest piece of hardware at its annual Worldwide Developers Conference on Monday as part of the stated ambition of CEO Tim Cook to grow services revenue to "the size of a Fortune 100 company" this year and then double it by 2020.

Pacific Crest Securities analyst Andy Hargreaves, who lowered his price forecast for the $800 billion company and cautioned on slowing iPhone sales, said he thinks the focus on the HomePod's performance as a speaker, rather than its tie-in to Apple services such as iTunes, Apple Care and iCloud, is an "indication that Apple lacks the proprietary services to match up well with in-home smart assistants from Amazon (AMZN) - Get Report and Alphabet  (GOOGL) - Get Report .

4. -- Shares in Toshiba rose in Tokyo after the Asahi newspaper reported the company is considering giving U.S. chipmaker Broadcom (AVGO) - Get Report  the exclusive rights to negotiate to buy the chip unit, Reuters reported.

Broadcom has teamed up with U.S. buyout firm Silver Lake in its bid for the chip business, sources told Reuters previously.

5. -- Roche (RHHBY)  shares fell the most in more than two years Tuesday after data that indicated a new form of breast cancer treatment by the Swiss drugmaker, which combined an older drug with a recently developed one, had only a limited impact on patients.

The three-year APHINITY trial showed that using two Roche drugs in combination -- Herceptin and Perjeta -- resulted in only marginally better results for women suffering an early form of breast cancer than those treated only with Herceptin and a placebo. The APHINITY data was announced Monday at the American Society of Clinical Oncology annual meeting.  

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