MADRID, 20 giugno (Reuters) - Spain's Treasury announced the following results at Thursday's bond auction where it sold 3.49 billion euros of bonds. Following are the details of the sale in millions of euros: Oct. 31, 2021 bond LATEST PREVIOUS AUCTION DATE June 20, 2019 June 6, 2019 ISSUE MATURITY Oct. 31, 2021 Oct. 31, 2021 COUPON (%) 0.05 0.05 HIGHEST YIELD (%) -0.400 -0.357 AVERAGE YIELD (%) -0.408 -0.361 AVERAGE PRICE 101.090 100.991 TOTAL BIDS (MLN) 2,210 3,475 ALLOTTED (MLN) 1,178 1,335 BID/COVER RATIO 1.9 2.6 July 30, 2024 bond LATEST PREVIOUS AUCTION DATE June 20, 2019 June 6, 2019 ISSUE MATURITY July 30, 2024 July 30, 2024 COUPON (%) 0.25 0.25 HIGHEST YIELD (%) -0.172 -0.090 AVERAGE YIELD (%) -0.182 -0.096 AVERAGE PRICE 102.215 101.783 TOTAL BIDS (MLN) 1,742 2,835 ALLOTTED (MLN) 825 1,110 BID/COVER RATIO 2.1 2.6 July 30, 2035 bond LATEST PREVIOUS AUCTION DATE June 20, 2019 May 23, 2019 ISSUE MATURITY July 30, 2035 July 30, 2035 COUPON (%) 1.85 1.85 HIGHEST YIELD (%) 0.890 1.475 AVERAGE YIELD (%) 0.883 1.466 AVERAGE PRICE 114.440 105.483 TOTAL BIDS (MLN) 2,118 1,688 ALLOTTED (MLN) 1,488 1,343 BID/COVER RATIO 1.4 1.3