def extract_top_capabilities(capabilities):
    """
    Extract top capabilities based on performance metrics.

    Parameters:
    - capabilities (list): List of tuples containing capability data.

    Returns:
    - tuple: Top capability with highest performance metric value.
    """
    return max(capabilities, key=lambda x: x[1])

# Example usage
capabilities = [('v5_1768236144', 108217.11959687909, 721, 15009.3),
                ('v5_1768235312', 89435.63603047856, 734, 12184.7),
                ('v5_1768235983', 98379.19963352643, 987, 9967.5)]

top_capability = extract_top_capabilities(capabilities)
print(top_capability)  # Output: ('v5_1768236144', 108217.11959687909, 721, 15009.3)