<?php

function shortcode_ticker( $attr, $content ) {

    // Start the output buffer. This allows us use normal
    // markup while setting it to a variable.
    ob_start();

    ?>

    <div class="test">
    Some test content
    </div>

    <?php

    $output = ob_get_contents();

    ob_end_clean();

    return $output;
}

add_shortcode( 'ticker', 'shortcode_ticker' );
?>