Confusion with for loop

Below is my code in which i am considering data file fb2010. At the end I have a matrix "resd". Now I want to add another three file fb2020, fb2030, fb2040. The code should be the same but including other three data files. At the end i should have four matrix like "resd"(including resd). So how to apply for loop. I tried to apply but it 's not working. Thanks in advance.

load('fb2010');                                    % loading the data

x = fb2010(3:1:1502,:);
% y_filt = filter(b,a,x);                          % filtering the received signal
y_filt= filter(b,a,x,[],2);
%%%%%%% fourier transform
nfft = length(y_filt);
res = fft(y_filt,nfft,2)/nfft;
res2 = res(:,1:nfft/2+1);                           %%%%taking single sided spectrum
res3 = fft(res2,[],2);

for i = 3:1:1500                         %%%%dividing each row by first row.
 resd(i,:) = res3(i,:)./res3(1,:);
end

Answer 1

[Matt J]

 Files={'fb2010','fb2020', 'fb2030', 'fb2040'};

 for k=1:length(Files);

        S=load(Files{i});      
        x = S.(Files{i})(3:1502,:);

           ....

        for i = 3:1500                                  
         resd(i,:,k) = res3(i,:)./res3(1,:);
        end

 end

[Matt J]

Better. Replace the inner loop

        for i = 3:1500                                  
         resd(i,:,k) = res3(i,:)./res3(1,:);
        end

with a bsxfun operation,

   resd(3:1500,:,k ) = bsxfun(@rdivide,res3(3:1500,:),res3(1,:));

[Mayank Lakhani]

Thanks Matt for the Answer.