* Canadian dollar weakens 0.3% against the greenback * Touches its weakest level since July 21 at 1.2630 * Canadian housing starts fall 3.2% in July * Canadian 10-year yield hits a near two-week low at 1.120% TORONTO, Aug 17 (Reuters) - The Canadian dollar on Tuesday weakened to its lowest level in nearly four weeks against its U.S. counterpart, as China"s crackdown on tech companies weighed on investor sentiment and domestic data showed a slowdown in housing starts. Global shares stumbled, rattled by concerns over China"s regulations for its once-freewheeling internet sector and a worldwide spike in COVID-19 infections driven by the Delta variant. Canada is a major producer of commodities, including oil, so its economy is sensitive to the global economic outlook. Oil was headed for a fourth day of losses. U.S. crude prices were down 0.8% at $66.74 a barrel, while the Canadian dollar was trading 0.3% lower at 1.2607 to the greenback, or 79.32 U.S. cents. The currency touched its weakest since July 21 at 1.2630. Canadian housing starts fell 3.2% in July compared with the previous month as a drop in multiple urban starts outweighed an increase in single-detached urban ones, data from the national housing agency showed. Domestic inflation data is due on Wednesday, which could offer clues on the Bank of Canada"s policy outlook. Investors may also pay some attention to Canada"s election campaign. On Monday, the main opposition Conservative Party set out its platform, pledging to bring back jobs lost to the COVID-19 pandemic and to balance the federal budget within 10 years. Canadian government bond yields were mixed across a flatter curve. The 10-year hit its lowest level since Aug. 4 at 1.120% before recovering to 1.140%, down 2.5 basis points on the day. (Reporting by Fergal Smith; Editing by Bernadette Baum) Our Standards: The Thomson Reuters Trust Principles.